Nonchalant hirsute leader removed
I believe the answer is:
airy
'nonchalant' is the definition.
(I've seen this in another clue)
'hirsute leader removed' is the wordplay.
'hirsute' becomes 'hairy' (synonyms).
'leader removed' means to remove the first letter.
'hairy' with its first letter removed is 'AIRY'.
(Other definitions for airy that I've seen before include "Well-ventilated; delicate" , "'Up the . . . . mountain / Down the rushy glen' (William Allingham)" , "Well ventilated; insubstantial" , "Open and spacious" , "(Of ideas) speculative" .)