Cut down on relaxation after December -- right? (8)
I believe the answer is:
decrease
'cut down' is the definition.
(thesaurus)
'relaxation after december right?' is the wordplay.
'relaxation' becomes 'ease' ('ease' can be a synonym of 'relaxation').
'after' says to put letters next to each other.
'december' becomes 'dec' ('Dec' can be a synonym of 'december').
'right?' becomes 'r' (common abbreviation).
'dec'+'r'='decr'
'ease' put after 'decr' is 'DECREASE'.
'on' is the link.
(Other definitions for decrease that I've seen before include "Make or become less" , "Get less" , "Smooth" , "Deminish, lessen" , "drop" .)