Multiple events, then a cold snap (9)
I believe the answer is:
decathlon
'multiple events' is the definition.
(athletics discipline comprising five events)
'then a cold snap' is the wordplay.
'snap' indicates an anagram (letters snap or break).
'then'+'a'+'cold'='thenacold'
'thenacold' is an anagram of 'DECATHLON'.
(Other definitions for decathlon that I've seen before include "Athletic event" , "sporting contest" , "Series of events" , "Olympic athletics event" , "Event, or events" .)