Cork, when top’s blown, will do for stylish hat (6)
I believe the answer is:
topper
'stylish hat' is the definition.
(top hat)
'cork when top's blown' is the wordplay.
'cork' becomes 'stopper' (a cork stops a bottle).
'when top's blown' means to remove the first letter.
'stopper' with its first letter taken off is 'TOPPER'.
'will do for' acts as a link.
(Other definitions for topper that I've seen before include "Executioner" , "good sort" , "Hat for formal occasions" , "lid" , "Formal headgear" .)