Happy laughing about advertisement (7)
I believe the answer is:
radiant
'happy' is the definition.
(thesaurus)
'laughing about advertisement' is the wordplay.
'laughing' becomes 'riant' ('riant' can be a synonym of 'laughing').
'about' is an insertion indicator.
'advertisement' becomes 'ad' ('ad' can be a synonym of 'advertisement').
'riant' placed around 'ad' is 'RADIANT'.
(Other definitions for radiant that I've seen before include "Splendid; heater type" , "Dazzling" , "Resplendent" , "Brilliant" , "glowing with happiness" .)