Drunken idiot receiving Murray's first service (4,4)
I believe the answer is:
high mass
'service' is the definition.
(I've seen this before)
'drunken idiot receiving murray's first' is the wordplay.
'drunken' becomes 'high' (high can informally mean drunk).
'idiot' becomes 'ass' (both can mean a stupid person).
'receiving' means one lot of letters goes inside another.
'murray's first' becomes 'm' (1st letter of 'murray').
'high'+'ass'='highass'
'highass' going around 'm' is 'HIGH MASS'.
(Other definitions for high mass that I've seen before include "full service" , "Church service celebrated with music, incense etc" .)