Perfunctory kiss (4)
I believe the answer is:
peck
'perfunctory kiss' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for peck that I've seen before include "Bite lightly; a dry measure" , "Kiss; part of bushel" , "Kiss; old dry measure" , "Gregory" , "Perfunctory kiss" .)