Canvas blouses say feel bad (7)
I believe the answer is:
topsail
'canvas' is the definition.
(topsail is a kind of canvas)
'blouses say feel bad' is the wordplay.
'blouses say' becomes 'tops' (blouse is a kind of top).
'feel bad' becomes 'ail'.
'tops'+'ail'='TOPSAIL'
(Other definitions for topsail that I've seen before include "It's set high up on a sailing ship" , "Uppermost attachment of a vessel's rigging" , "Part of a ship's rigging" , "Upper piece of ship's canvas" , "sheet of canvas" .)