Bug water vole's eviscerated (5)
I believe the answer is:
peeve
'bug' is the definition.
(both can mean to annoy)
'water vole's eviscerated' is the wordplay.
'water' becomes 'pee' (synonyms).
'eviscerated' says to hollow out the word (remove centre letters) (the word is disembowelled of its inside letters).
'vole' with its centre removed is 've'.
'pee'+'ve'='PEEVE'
(Other definitions for peeve that I've seen before include "grouse" , "cause irritation" , "Get annoyed" , "bug" , "Cause resentment" .)