Want larvae gutted for bait (6)
I believe the answer is:
needle
'bait' is the definition.
(thesaurus)
'want larvae gutted' is the wordplay.
'want' becomes 'need' (synonyms).
'gutted' means to remove the middle letters (to gut something is to remove its insides).
'larvae' with its middle removed is 'le'.
'need'+'le'='NEEDLE'
'for' acts as a link.
(Other definitions for needle that I've seen before include "It points" , "Bug" , "Annoy; indicator" , "Instrument to annoy" , "joint" .)