Large Italian male, loose-limbed (5)
I believe the answer is:
lithe
'loose-limbed' is the definition.
(both can mean agile)
'large italian male' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'italian' becomes 'it' (abbreviation for Italian).
'male' becomes 'he' (he refers to a man).
'l'+'it'+'he'='LITHE'
(Other definitions for lithe that I've seen before include "Slim, graceful" , "light" , "Supple and limber" , "Supple and graceful" , "Physically flexible or supple" .)