Hear start of carol at church (5)
I believe the answer is:
catch
'hear' is the definition.
(catching is a kind of hearing)
'start of carol at church' is the wordplay.
'start of' says to take the initial letters.
'church' becomes 'ch' (common abbreviation).
The first letter of 'carol' is 'c'.
'c'+'at'+'ch'='CATCH'
(Other definitions for catch that I've seen before include "Understand" , "Desirable partner" , "Take hold of" , "Grab; trick; fastener" , "It's taken by a fielder to dismiss a player in baseball and cricket" .)