22 minutes, but with one wrong. Nice, gentle start to the 'daily' week. I'm adopting the 'Leave none behind' protocol from now on, so every answer will be given (hopefully, the right ones).
Across
1 SCORNFUL - anagram of 'of runs' round C[rater] + L[ake].
3 EN BLOC - NB in COLE (old word for cabbage - survives in coleslaw, indirectly if not directly).
10 DEFINITE ARTICLE
11 TIPSTER - TIPS+TE+R[edcar]; interesting one this. Redcar is a racecourse in Yorkshire, but the use of tout to mean tipster (for a little slice) is limited so far as I know to N. America. In England, it refers to a furtive looking man who speaks out of the corner of his mouth the single phrase 'Anybody wanna buya ticket?'
12 SCARLET - CARL (Zeiss) in SET; Herr Zeiss was a 19 C maker of optical instruments and founder of Carl Zeiss Jena - the company not the football team (which is how I'd heard of him).
13 MISPRINT - easy if you know that literal means, in printers' parlance, the misprint of a letter; not so easy if you saw it in a puzzle recently, made a mental note of it and then completely forgot it. I put 'pinpoint', knowing it was wrong but also knowing I could look at the clue for another ten minutes and not get it.
15 F+EVER
18 TIGHT - double definition, the first as in a tight corner.
20 TROMBONE - ROM in T-BONE; 'travellers' pop up in Times crosswords from time to time - watch out also for Roma, and, if the setter is particularly adept, Romany and Romani.
23 UP+STAGE
25 PER[S]ON+A
26 GOLDEN RETRIEVER - eventer girl rode*; pretty easy anagram given the anagrind 'bothered' and the definition.
27 EL NINO - anagram of 'online'.
28 CHARTRES - R[eliabl]E in CHARTS.
Down
1 SE+DATE - Kent is prototypically south-east in crosswordland.
2 OFFSPRING - OF+F[ine]+SPRING.
3 NONSTOP - N[oon] followed by ON+ST+OP, the literal being 'done without interruption'; more common with a hyphen when used as an adverb, perhaps, but when used as an adjective quite natural as one word.
5 UTTER - double definition, where positive means utter = downright as in 'positive disaster'. Liked this one for the prosodic twist, if that makes any sense.
6 NOT HALF
7 LOCAL - A+COL (reversed) + [spel]L; I always think of a col as just a pass, but technically it's the lowest point of a ridge connecting two peaks.
8 CREATURE - curate* + RE.
9 FALSETTO - SET-TO following FAL[l].
14 IN THEORY - IN (elected) followed by HE[r] in TORY.
16 VAN+CO[U(ruguay)]VER - I wasn't suckered by this one for long, though Montevideo did flash through my mind.
17 STRUGGLE - another dd, I reckon, with pains being used as in 'take pains'.
19 TRADE-IN - another anagram (trained*).
21 BARRIE+R
22 M[ADR]AS - Chicken Madras was the Chicken Tikka Masala of the 70s.
24 SALON - hidden(ish).
25 PITCH - P+IT+CH; this confused me at first, as 'in front of' would seem to indicate that the 'it' goes before the 'p', which would give 'itpch'; if I have parsed this correctly, the ambiguity of 'in front of' means that it could go either side of the 'p'. It confused me to the end, it seems, as mctext has a far more plausible explanation: lift and separate 'in front of' so that 'it' goes in 'P...ch', where 'P' stands for 'front of Presbyterian'.
Across
1 SCORNFUL - anagram of 'of runs' round C[rater] + L[ake].
3 EN BLOC - NB in COLE (old word for cabbage - survives in coleslaw, indirectly if not directly).
10 DEFINITE ARTICLE
11 TIPSTER - TIPS+TE+R[edcar]; interesting one this. Redcar is a racecourse in Yorkshire, but the use of tout to mean tipster (for a little slice) is limited so far as I know to N. America. In England, it refers to a furtive looking man who speaks out of the corner of his mouth the single phrase 'Anybody wanna buya ticket?'
12 SCARLET - CARL (Zeiss) in SET; Herr Zeiss was a 19 C maker of optical instruments and founder of Carl Zeiss Jena - the company not the football team (which is how I'd heard of him).
13 MISPRINT - easy if you know that literal means, in printers' parlance, the misprint of a letter; not so easy if you saw it in a puzzle recently, made a mental note of it and then completely forgot it. I put 'pinpoint', knowing it was wrong but also knowing I could look at the clue for another ten minutes and not get it.
15 F+EVER
18 TIGHT - double definition, the first as in a tight corner.
20 TROMBONE - ROM in T-BONE; 'travellers' pop up in Times crosswords from time to time - watch out also for Roma, and, if the setter is particularly adept, Romany and Romani.
23 UP+STAGE
25 PER[S]ON+A
26 GOLDEN RETRIEVER - eventer girl rode*; pretty easy anagram given the anagrind 'bothered' and the definition.
27 EL NINO - anagram of 'online'.
28 CHARTRES - R[eliabl]E in CHARTS.
Down
1 SE+DATE - Kent is prototypically south-east in crosswordland.
2 OFFSPRING - OF+F[ine]+SPRING.
3 NONSTOP - N[oon] followed by ON+ST+OP, the literal being 'done without interruption'; more common with a hyphen when used as an adverb, perhaps, but when used as an adjective quite natural as one word.
5 UTTER - double definition, where positive means utter = downright as in 'positive disaster'. Liked this one for the prosodic twist, if that makes any sense.
6 NOT HALF
7 LOCAL - A+COL (reversed) + [spel]L; I always think of a col as just a pass, but technically it's the lowest point of a ridge connecting two peaks.
8 CREATURE - curate* + RE.
9 FALSETTO - SET-TO following FAL[l].
14 IN THEORY - IN (elected) followed by HE[r] in TORY.
16 VAN+CO[U(ruguay)]VER - I wasn't suckered by this one for long, though Montevideo did flash through my mind.
17 STRUGGLE - another dd, I reckon, with pains being used as in 'take pains'.
19 TRADE-IN - another anagram (trained*).
21 BARRIE+R
22 M[ADR]AS - Chicken Madras was the Chicken Tikka Masala of the 70s.
24 SALON - hidden(ish).
25 PITCH - P+IT+CH; this confused me at first, as 'in front of' would seem to indicate that the 'it' goes before the 'p', which would give 'itpch'; if I have parsed this correctly, the ambiguity of 'in front of' means that it could go either side of the 'p'. It confused me to the end, it seems, as mctext has a far more plausible explanation: lift and separate 'in front of' so that 'it' goes in 'P...ch', where 'P' stands for 'front of Presbyterian'.