Initial pain merrily dealt with (11)
I believe the answer is:
preliminary
'initial' is the definition.
(I've seen this before)
'pain merrily dealt with' is the wordplay.
'dealt with' indicates anagramming the letters.
'pain'+'merrily'='painmerrily'
'painmerrily' anagrammed gives 'PRELIMINARY'.
(Other definitions for preliminary that I've seen before include "Initial -- action before the main event" , "First" , "Introductory (measure or statement)" , "Done in preparation" , "Minor match before the main event" .)