Contact (5)
'contact' is the definition.
(I know that touch is a type of contact)
This is the entire clue.
(Other definitions for touch that I've seen before include "Side beyond playing area" , "Feel - brush" , "small quantity" , "Deal with" , "Make physical contact" .)
(Other definitions for lens that I've seen before include "One focusing light" , "City of northern France: periscope part" , "Piece of glass, usually curved" , "Through which to view" , "Dark cloud; shining light" .)
(Other definitions for lenses that I've seen before include "Eye parts" , "Camera attachments" , "They could help you see" , "They're transparent in the eye" , "The glasses in spectacles" .)