A number of leaders in Eastern Italy granted housing to youths (6)
I believe the answer is:
eighty
'a number' is the definition.
(eighty is a kind of number)
'leaders in eastern italy granted housing to youths' is the wordplay.
'leaders in' suggests taking the first letters.
The first letters of 'eastern italy granted housing to youths' is 'EIGHTY'.
'of' acts as a link.
(Other definitions for eighty that I've seen before include "not many score" , "XXC" , "Rather old" , "score less than a hundred" , "Fourscore" .)