Wild critter's small bounds (9)
I believe the answer is:
restricts
'bounds' is the definition.
(I know this)
'wild critter's small' is the wordplay.
'wild' is an anagram indicator.
'small' becomes 's' (abbreviation - e.g. clothes size).
'critters' is an anagram of 'restrict'.
'restrict'+'s'='RESTRICTS'
(Other definitions for restricts that I've seen before include "Puts a limit on" , "Places limits on" .)