Smile at Ray (4)
I believe the answer is:
beam
I believe this clue is a double definition.
'smile' is the first definition.
(to beam is to smile)
'ray' is the second definition.
(I know that ray can be written as beam)
'at' is the link.
(Other definitions for beam that I've seen before include "Gymnast's bar; broad smile" , "Supporting piece of wood - shaft of light" , "one gets from the Sun" , "Wide grin" , "Ray; structural timber" .)