Broad smile (4)
'broad smile' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for beam that I've seen before include "one gets from the Sun" , "Smile, transmit (radio signal)" , "Smile broadly; plank" , "Smile brightly - supporting timber" , "Ray of light or a large smile" .)
'broad smile' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for grin that I've seen before include "Cheesy smile?" , "Look happy" , "Accept with good grace - . . . . and bear it" , "Toothy smile" , "Smile wryly" .)