Light touch from one X represents (4)
I believe the answer is:
kiss
I believe this clue is a double definition.
'light touch' is the first definition.
(kiss can mean to brush against lightly)
'one x represents' is the second definition.
(X can mean a kiss)
'from' acts as a link.
(Other definitions for kiss that I've seen before include "Embrace" , "Eg, smacker, peck" , "drop of wax" , "Neck - peck" , "Affectionate greeting" .)