Make merry getting fifty on merry-go-round (8)
I believe the answer is:
carousel
'merry-go-round' is the definition.
(synonyms)
'make merry getting fifty' is the wordplay.
'make merry' becomes 'carouse' (carousing is a kind of making merry).
'getting' says to put letters next to each other.
'fifty' becomes 'l' (Roman numeral).
'carouse'+'l'='CAROUSEL'
'on' is the link.
(Other definitions for carousel that I've seen before include "A closure (anag.)" , "fairground entertainment" , "luggage mover at Heathrow?" , "Baggage conveyor" , "Revolving belt for luggage at airport" .)