Round of cards — fast one (5)
I believe the answer is:
trick
This clue is a double definition.
'round of cards' is the first definition.
(term for a round of cards played in bridge)
'fast one' is the second definition.
(synonyms)
(Other definitions for trick that I've seen before include "Stratagem to take at cards" , "Kid" , "Con" , "Round of played cards" , "Hoax; knack" .)