Small sailor, embarrassed, had leading role (7)
I believe the answer is:
starred
'had leading role' is the definition.
'starred' can be an answer for 'had' (starring is a kind of having). I also know that both 'leading' and 'role' relate to this answer.
'small sailor embarrassed' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'sailor' becomes 'tar' (slang term for a sailor).
'embarrassed' becomes 'red' (someone may blush or go red when embarrassed).
's'+'tar'+'red'='STARRED'
(Other definitions for starred that I've seen before include "took the lead part" , "featured prominently" , "Took leading role" , "Took the lead role" .)