Land on the sunny side (5)
I believe the answer is:
This clue is a triple definition!
'land' is the first definition.
(lighting is a kind of landing)
'on' acts as a link.
'the sunny' is the second definition.
'side' is the third definition.
(Other definitions for light that I've seen before include "Brightness" , "Undemanding; crossword answer" , "Not too demanding" , "solution to clue" , "not profound" .)