Smiles at rays (5)
I believe the answer is:
Here is my best explanation:
This clue is a double definition.
'smiles' is the first definition.
(beaming is a kind of smiling)
'rays' is the second definition.
('beam' can be a synonym of 'ray')
'at' is the link.
(Other definitions for beams that I've seen before include "Shines", "Smiles broadly or sunnily", "rays", "Smiles; joists" and "Rays of light".)