Insect with acerbic taste brought up (4)
I believe the answer is:
gnat
'insect' is the definition.
(I know that gnat is a type of mosquito)
'taste brought up' is the wordplay.
'taste' becomes 'tang' (tang is a kind of taste).
'brought up' says the letters should be written backwards (in a down clue, letters go up).
'tang' in reverse letter order is 'GNAT'.
'with acerbic' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for gnat that I've seen before include "Tang of a biting fly" , "Small biter" , "a little bit of a nuisance" , "Midge, mosquito" , "Small, swarming insect" .)