Quit when holiday's cancelled (5,3)
I believe the answer is:
'quit' is the definition.
(I know this)
'holiday's cancelled' is the wordplay.
'holiday' becomes 'leave' (I've seen this before).
'cancelled' becomes 'off' (similar in meaning).
'when' is the link.
(Other definitions for leave off that I've seen before include "not eating or drinking" , "Cease, or shed garment" , "Give over!" .)