It's cold, there's a Santa all dressed up and entertainment (7)
I believe the answer is:
canasta
'all dressed up and entertainment' is the definition.
I can't judge whether this definition defines the answer.
'it's cold there's a santa' is the wordplay.
'it's cold' becomes 'C' (eg on taps).
'there's' is a charade indicator (letters next to each other).
'a' becomes 'an'.
'santa' becomes 'asta' (I can't explain this - if you can you should give a lot more credence to this answer).
'c'+'an'+'asta'='CANASTA'
Can you help me to learn more?
(Other definitions for canasta that I've seen before include "Decorated with artificial jewels" , "Card game like rummy" , "Can a staff cook stomach game?" , "Form of rummy using two decks of cards and four jokers" , "Card game resembling rummy" .)