Cryptic answer by the setter in trousers, etc (8)
I believe the answer is:
menswear
'trousers etc' is the definition.
'cryptic answer by the setter' is the wordplay.
'cryptic' is an anagram indicator (I've seen this in other clues).
'by' means one lot of letters go next to another.
'the setter' becomes 'me' (the setter of the clue).
'answer' anagrammed gives 'nswear'.
'nswear' after 'me' is 'MENSWEAR'.
'in' acts as a link.
(Other definitions for menswear that I've seen before include "Boxers, for example" , "Suits, shirts, ties etc" , "Male attire" , "Male clothing" , "uniform, perhaps" .)