Kiss Dot, heading off (4)
I believe the answer is:
peck
'kiss' is the definition.
(I know this)
'dot heading off' is the wordplay.
'dot' becomes 'speck' (I've seen this before).
'heading off' means to remove the first letter.
'speck' with its initial letter taken off is 'PECK'.
(Other definitions for peck that I've seen before include "Bite lightly; a dry measure" , "Attack with beak" , "Large number" , "One quarter of a bushel" , "Light kiss; measure" .)