Mean to transform some hair (4)
I believe the answer is:
mane
'some hair' is the definition.
(mane is a kind of hair)
'mean to transform' is the wordplay.
'to transform' indicates an anagram.
'mean' is an anagram of 'MANE'.
(Other definitions for mane that I've seen before include "Neck hair of an animal" , "(Lion's) hair on neck" , "Long shaggy hair" , "Hair (of lion)" , "Long thick hair" .)