Great bit of coiffure with king leaving church (3-5)
I believe the answer is:
top-notch
'great' is the definition.
(both can mean excellent)
'bit of coiffure with king leaving church' is the wordplay.
I cannot really understand how this works, but
'bit' could be 'o' (resembles 0, a binary digit or bit) and 'o' is found in the answer.
'of' could be 'o' and 'o' is located in the answer.
'church' could be 'ch' (common abbreviation) and 'ch' is present in the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for top-notch that I've seen before include "Excellent (informal)" , "Wonderful" , "Grade 1" , "Superb" , "First-rate" .)