Buss (4)
I believe the answer is:
kiss
'buss' is the definition.
(I know that buss can be written as kiss)
This is all the clue.
(Other definitions for kiss that I've seen before include "Greet with lips" , "Cross" , "Peck (on cheek or lips?)" , "Touch lightly - a sign of affection" , "Evidence of romance" .)