Bishop, worn out, blustered (7)
I believe the answer is:
bragged
'blustered' is the definition.
('brag' can be a synonym of 'bluster')
'bishop worn out' is the wordplay.
'bishop' becomes 'b' (abbreviation used in chess).
'worn out' becomes 'ragged'.
'b'+'ragged'='BRAGGED'
(Other definitions for bragged that I've seen before include "Boasted" , "Crew" , "Blew one's own trumpet" .)