Oblong cream puff (6)
I believe the answer is:
eclair
'oblong cream puff' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for eclair that I've seen before include "Finger-shaped cream-filled cake of choux pastry" , "A relic (anag)" , "Long cream puff" , "Dainty" , "Long thin cake with chocolate and cream" .)