Quiet time for Carol (6,5)
I believe the answer is:
silent night
'carol' is the definition.
(I've seen this before)
'quiet time' is the wordplay.
'quiet' becomes 'silent' (similar in meaning).
'time' becomes 'night' (night is a kind of time).
'silent'+'night'='SILENT NIGHT'
'for' is the link.
(Other definitions for silent night that I've seen before include "Christmas carol - hours of undisturbed sleep?" , "Blood sucking mammals" .)