A Democrat stops laughing and beaming (7)
I believe the answer is:
radiant
'beaming' is the definition.
('radiant' can be a synonym of 'beaming')
'a democrat stops laughing' is the wordplay.
'democrat' becomes 'd'.
'stops' indicates putting letters inside.
'laughing' becomes 'riant' ('riant' can be a synonym of 'laughing').
'a'+'d'='ad'
'ad' put within 'riant' is 'RADIANT'.
'and' acts as a link.
(Other definitions for radiant that I've seen before include "Shining; joyful" , "Bright" , "Beautiful" , "Shining brightly, being at nadir" , "looking happy" .)