Time to go around monster (5)
I believe the answer is:
troll
'monster' is the definition.
(I know that troll is a type of mythical creature)
'time to go' is the wordplay.
'time' becomes 't' (abbreviation).
'to go' becomes 'roll' (rolling is a kind of going).
't'+'roll'='TROLL'
'around' is the link.
(Other definitions for troll that I've seen before include "Bad fairy (giant or dwarf)" , "Ugly Norse dwarf" , "In Scandinavia, a mythical giant or dwarf" , "Online annoyance" , "Scandinavian dwarf or giant" .)