Verbally attack a burrowing rodent (6)
I believe the answer is:
gopher
'a burrowing rodent' is the definition.
(gopher is a type of rodent)
'verbally attack' is the wordplay.
'verbally' shows a homophone (sound like).
'attack' becomes 'go for' (go for can mean to attack).
'gofor' is a homophone of 'GOPHER'.
(Other definitions for gopher that I've seen before include "small animal" , "Burrowing rodent of north and central America" , "Rodent with large cheek pouches" , "skilled digger" , "Method of teaching reading by sounds" .)