In a lively dance, five make merry (5)
I believe the answer is:
revel
'make merry' is the definition.
(synonyms)
'in a lively dance five' is the wordplay.
'in' is an insertion indicator.
'a lively dance' becomes 'reel' (I've seen this before).
'five' becomes 'V' (Roman numeral).
'reel' placed around 'v' is 'REVEL'.
(Other definitions for revel that I've seen before include "Celebrate noisily" , "Have noisy fun" , "Riotous feast" , "Paint the town red" , "Carouse" .)