Cold holiday split (6)
I believe the answer is:
cleave
'split' is the definition.
('cleave' can be a synonym of 'split')
'cold holiday' is the wordplay.
'cold' becomes 'c' (eg on taps).
'holiday' becomes 'leave' (I've seen this before).
'c'+'leave'='CLEAVE'
(Other definitions for cleave that I've seen before include "Split apart - stick together" , "Split or cling to" , "Chop or split" , "Unite together; split apart" , "To separate and to adhere" .)