Sunny smile? (4)
I believe the answer is:
beam
'smile?' is the definition.
(beam can mean to smile)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for beam that I've seen before include "Ray; structural timber" , "Sturdy timber" , "Shine" , "Ray; piece of timber" , "Light - heavy timber - wide smile" .)