Before kiss, take off top (4)
I believe the answer is:
apex
'top' is the definition.
(apex is a top or peak)
'before kiss take off' is the wordplay.
'before' says to put letters next to each other.
'kiss' becomes 'x' (X can represent a kiss).
'take off' becomes 'ape' (I've seen this before).
'x' put after 'ape' is 'APEX'.
(Other definitions for apex that I've seen before include "high-point" , "Top, highest part" , "The highest point of something" , "Uppermost tip" , "Pointed top" .)