In time the Italian becomes nimble (5)
I believe the answer is:
agile
'nimble' is the definition.
(agile can mean nimble or athletic)
'in time the italian' is the wordplay.
'in' is an insertion indicator.
'time' becomes 'age' (an age is a period of time).
'the italian' becomes 'il' (Italian for 'the').
'age' enclosing 'il' is 'AGILE'.
'becomes' is the link.
(Other definitions for agile that I've seen before include "Nimble, fleet" , "athletic" , "Nifty" , "Nimble, quick-moving" , "Quick in movement" .)