Wild growth in free line dance (9)
I believe the answer is:
celandine
'wild growth' is the definition.
(celandine is a wild plant)
'free line dance' is the wordplay.
'free' indicates an anagram.
'line'+'dance'='linedance'
'linedance' is an anagram of 'CELANDINE'.
'in' acts as a link.
(Other definitions for celandine that I've seen before include "Flowering plant - decennial (anag)" , "Land niece with the swallowwort." , "Plant of buttercup family" , "... one blooming" .)