Source of light lead (4)
I believe the answer is:
star
I believe this clue is a double definition.
'source of light' is the first definition.
(thesaurus)
'lead' is the second definition.
(synonyms)
(Other definitions for star that I've seen before include "Main attraction" , "Eg, Antares" , "chamber" , "appear above others?" , "Pointed shape" .)