Prepares for holiday: two join the scrum (5)
I believe the answer is:
packs
This clue is a double definition.
'prepares for holiday' is the first definition.
'two join the scrum' is the second definition.
(a rugby scrum includes two packs)
(Other definitions for packs that I've seen before include "Given cards" , "lots of cards" , "Cartons" , "Prepares gifts, say" , "Groups of hunting animals" .)