Exterminator's target (3)
'exterminator's target' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for pest that I've seen before include "Destructive insect or nuisance" , "Destructive creature" , "Constant nuisance" , "Annoying nuisance" , "Troublesome man or animal" .)
(Other definitions for ant that I've seen before include "` `Go to the ... thou sluggard' '" , "one living in colonies" , "Proverbially hard-working insect" , "maybe in hill" , "One working hard" .)