Eat away, using some of the rodents teeth (5)
I believe the answer is:
erode
'eat away' is the definition.
(I know that eat away can be written as erode)
'some of the rodents teeth' is the wordplay.
'some of' indicates a hidden word.
'ERODE' is hidden within 'the rodents teeth'.
'using' acts as a link.
(Other definitions for erode that I've seen before include "Wear away with weather" , "Grind down" , "Eat away" , "Abrade" , "go to pieces!" .)