Crew's leader in boat worn out (7)
I believe the answer is:
bragged
'crew's' is the definition.
(I've seen this before)
'leader in boat worn out' is the wordplay.
'leader in' says to take the initial letters.
'worn out' becomes 'ragged'.
The initial letter of 'boat' is 'b'.
'b'+'ragged'='BRAGGED'
(Other definitions for bragged that I've seen before include "Blew one's own trumpet" , "Crew" , "Boasted" .)