Squirrel, perhaps not red, frisky (6)
I believe the answer is:
rodent
'squirrel perhaps' is the definition.
(squirrel is a kind of rodent)
'not red frisky' is the wordplay.
'frisky' indicates anagramming the letters.
'not'+'red'='notred'
'notred' anagrammed gives 'RODENT'.
(Other definitions for rodent that I've seen before include "Eg, capybara" , "Animal such as a mouse" , "Small gnawing mammal" , "Rat perhaps" , "Small gnawing animal" .)