Chewed like a rodent (6)
I believe the answer is:
gnawed
'chewed like a rodent' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for gnawed that I've seen before include "Bit persistently at something hard" , "Bit or chewed persistently" , "Worried persistently" , "Chewed at like dog with bone" , "Nibbled - chewed" .)