Throws light on alley, as characters in Strip Mall are back (4)
I believe the answer is:
lamp
'throws light on alley' is the definition.
'characters in strip mall are back' is the wordplay.
'characters in' says the answer is hidden in the clue.
'are back' says the letters should be written in reverse.
'pmal' is hidden in the letters of 'strip mall'.
'pmal' written backwards gives 'LAMP'.
'as' acts as a link.
(Other definitions for lamp that I've seen before include "Artificial source of illumination" , "Source of light, usually portable" , "Device providing illumination" , "Florence Nightingale was the Lady with the . . . ." , "punch" .)