Hired soldier is gleeful about broken cane (9)
I believe the answer is:
mercenary
'hired soldier' is the definition.
(I've seen this before)
'gleeful about broken cane' is the wordplay.
'gleeful' becomes 'merry' (I've seen this in another clue).
'about' is an insertion indicator.
'broken' indicates anagramming the letters.
'cane' with letters rearranged gives 'cena'.
'merry' placed around 'cena' is 'MERCENARY'.
'is' is the link.
(Other definitions for mercenary that I've seen before include "Professional soldier hired by foreign country" , "One who fights for foreign country for pay" , "Professional soldier serving in a foreign army" , "Soldier for hire" , "Bent on making money" .)