It's able to grow wild like an animal (7)
I believe the answer is:
bestial
'like an animal' is the definition.
(I've seen this in another clue)
'it's able to grow wild' is the wordplay.
'to grow wild' is an anagram indicator (I've seen 'growing wild' mean this).
'its'+'able'='itsable'
'itsable' is an anagram of 'BESTIAL'.
(Other definitions for bestial that I've seen before include "for animals?" , "Animal-like" , "Brutish or cruel, hardly human" , "Tables I create, being brutal or cruel" , "Savage" .)