Different pincer up, nipping old rodent (9)
I believe the answer is:
porcupine
'rodent' is the definition.
(I know that porcupine is a type of rodent)
'different pincer up nipping old' is the wordplay.
'different' is an anagram indicator.
'nipping' indicates putting letters inside (inserted letters are bitten or nipped).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'pincer'+'up'='pincerup'
'pincerup' with letters rearranged gives 'prcupine'.
'prcupine' going around 'o' is 'PORCUPINE'.
(Other definitions for porcupine that I've seen before include "Spiny creature" , "prickly type" , "Spiny animal" , "Large spiny rodent" , "Rodent with sharp bristles" .)