Juliet, to Romeo (3)
I believe the answer is:
sun
'juliet to romeo' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sun that I've seen before include "Source of light and heat" , "Dawn riser" , "Major star" , "Fireball 93,000,000 miles away" , "Get a tan" .)