Celebration may be fast and live (8)
I believe the answer is:
festival
'celebration' is the definition.
(I know that festival is a type of celebration)
'may be fast and live' is the wordplay.
'may be' indicates an anagram.
'and' means one lot of letters go next to another.
'fast'+'live'='fastlive'
'fastlive' with letters rearranged gives 'FESTIVAL'.
(Other definitions for festival that I've seen before include "Religious feast" , "Carnival or jamboree" , "Lift vase (anag.)" , "holiday?" , "Celebration, religious or artistic" .)