Acerbic worker, say, beside dyke (9)
I believe the answer is:
trenchant
'acerbic' is the definition.
(I've seen this before)
'worker say beside dyke' is the wordplay.
'worker say' becomes 'ant' (worker is a type of ant).
'beside' means one lot of letters go next to another (I've seen this in other clues).
'dyke' becomes 'trench' (I can't explain this - if you can you should believe this answer much more).
'ant' after 'trench' is 'TRENCHANT'.
Can you help me to learn more?
(Other definitions for trenchant that I've seen before include "Vigorous, incisive" , "Clear" , "Incisive in style" , "Showing keenness" , "caustic?" .)