Sour recluse is heard (6)
I believe the answer is:
acetic
'sour' is the definition.
(I've seen this in another clue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for acetic that I've seen before include "Like vinegar's acid" , "sort of acid" , "really sour" , "Colourless pungent acid" , "Type of acid derived from vinegar" .)