Rebuff despite a promising start in the dance (5)
I believe the answer is:
repel
'rebuff' is the definition.
('repel' can be a synonym of 'rebuff')
'a promising start in the dance' is the wordplay.
'start' suggests taking the first letters.
'in the' means one lot of letters goes inside another.
'dance' becomes 'reel' (reel is a kind of dance).
The first letter of 'promising' is 'p'.
'p' inserted into 'reel' is 'REPEL'.
'despite' is the link.
(Other definitions for repel that I've seen before include "may turn your stomach" , "Turn away" , "Successfully resist" , "Drive back like leper" , "Drive back - revolt" .)