Smile and support (4)
I believe the answer is:
beam
This clue is a double definition.
'smile' is the first definition.
(beam can mean to smile)
'support' is the second definition.
(I know that beam is a type of structural member)
'and' is the link.
(Other definitions for beam that I've seen before include "Smile; piece of timber" , "Smile radiantly" , "Ray; structural timber" , "one gets from the Sun" , "Radiant smile; timber support" .)