Store to have to keep one in always for Christmas, say (4,7)
I believe the answer is:
bank holiday
'christmas say' is the definition.
(Christmas is a bank holiday)
'store to have to keep one in always' is the wordplay.
'store' becomes 'bank' (I've seen this before).
'to have to' becomes 'i' (I can't explain this - if you can you should believe this answer much more).
'keep' becomes 'hold' (both can mean to have or possess something).
'one in' is an insertion indicator.
'always' becomes 'ay'.
'i' inserted into 'hold' is 'holid'.
'bank'+'holid'+'ay'='BANK HOLIDAY'
'for' is the link.
(Other definitions for bank holiday that I've seen before include "Public day off" , "National day off" .)