Giant Italian wearing brown (5)
I believe the answer is:
titan
'giant' is the definition.
('titan' can be a synonym of 'giant')
'italian wearing brown' is the wordplay.
'italian' becomes 'it'.
'wearing' is an insertion indicator.
'brown' becomes 'tan' (tan is a kind of brown).
'it' put inside 'tan' is 'TITAN'.
(Other definitions for titan that I've seen before include "Saturn's moon" , "Atlas, say" , "Giant -- rocket" , "Mythological giant" , "One of the first pantheon of Greek deities" .)