Across
One offering unwanted advice to support troubled advertiser (4-4,6)
Mathematician’s principle, first to last attached to basis of logarithms (5)
I haven't cracked this one yet — but Fifteensquared have:
E (e, base of natural logs – actually named after Euler) + RULE with the R moved to the end
Date energy stabilised (2,6)
Being caught probing religious ascetic (7)
I haven't cracked this one yet — but Fifteensquared have:
C in ESSENE
Program linked to a reduced kind of plants (7)
I haven't cracked this one yet — but Fifteensquared have:
BOT (type of computer program) + A NIC[e]
Short comic piece brother’s written capturing Queen (5)
Players in soccer game forming line on another pitch? (6-3)
Keen frost wrecked fasteners (4,5)
US farm subdivision not opening for business (5)
I haven't cracked this one yet — but Fifteensquared have:
BRANCH less B[usiness]
Performing for men in unit (7)
Look at sites, backing corporation’s slice (7)
Spring not entirely long? There’s an extra day in it (4,4)
Krypton, oxygen, neon and tin from Scandinavia (5)
Twice note collapses in funds for Durham town (8-2-4)
Down
A night at the pub may give you it when you want it (7,5)
Drinks cold water on leaving bar upset (5)
I haven't cracked this one yet — but Fifteensquared have:
C + reverse of SALOON less ON
Release volume dismissing an old rugby player (9)
I haven't cracked this one yet — but Fifteensquared have:
SPRING (release, e.g. from prison) + BOOK less one of the Os (“an old”). The Springboks are the South African rugby union team
After a month, satisfied to receive new increase (7)
I haven't cracked this one yet — but Fifteensquared have:
AUG[ust] + N in MET
Stop papers reversing demand about book (7)
I haven't cracked this one yet — but Fifteensquared have:
Reverse of ID (papers) + B in SALE (“demand, volume of selling” says Chambers)
Still no start of better time (5)
I haven't cracked this one yet — but Fifteensquared have:
[f]INER + T. This always reminds me of Sir Humphrey in Yes, Minister struggling to explain what an inert compound is, and finally saying “well, it’s not … ert”, after which Bernard mutters “wouldn’t ert a fly”
Scientist’s wife abandoning marriage fashion (9)
I haven't cracked this one yet — but Fifteensquared have:
WEDDING less W + TON (fashion)
Unexpectedly chose to inhale pot – resounding effects in these places (4,8)
A Parisienne and American together, mostly sleeping? Extremely disquieting (9)
I haven't cracked this one yet — but Fifteensquared have:
UNE (French “A”) + A[merican) + SIEST[a]
Extravagant dish largely avoided during occasion (9)
Finished early race, skipping second part of Cheddar Gorge (7)
I haven't cracked this one yet — but Fifteensquared have:
OVER (finished) + HEAT (an early race) less [c]H[eddar]
Colourful parts of plant, small and mainly slight (7)
Jelly son consumed in a shot (5)
I haven't cracked this one yet — but Fifteensquared have:
S in A PIC (photo, shot)
Figure of speech elevated by English Left (5)
I haven't cracked this one yet — but Fifteensquared have:
Reverse of E PORT
Type letters or click words in the clue