I make a mistake filling receptacle for clown (7)
I believe the answer is:
pierrot
'clown' is the definition.
(I've seen this before)
'i make a mistake filling receptacle' is the wordplay.
'make a mistake' becomes 'err' ('err' can be a synonym of 'make a mistake').
'filling' is an insertion indicator.
'receptacle' becomes 'pot' (I've seen this before).
'i'+'err'='ierr'
'ierr' inserted into 'pot' is 'PIERROT'.
'for' acts as a link.
(Other definitions for pierrot that I've seen before include "Clown from French pantomime with white face and costume - tripe or what?" , "Aged entertainer" , "I report on French pantomime clown" , "Type of clown" , "Male clown from French pantomime" .)