Light left during riotous dance (6)
I believe the answer is:
candle
'light' is the definition.
(candle is a kind of light)
'left during riotous dance' is the wordplay.
'left' becomes 'l' (common abbreviation).
'during' means one lot of letters goes inside another.
'riotous' indicates an anagram.
'dance' with letters rearranged gives 'cande'.
'l' going into 'cande' is 'CANDLE'.
(Other definitions for candle that I've seen before include "Wax cylinder" , "Old form of illumination" , "may be too expensive for game" , "Lanced in light" , "Lanced (anag)" .)