Laughing Scotsman in outskirts of Rabat (5)
I believe the answer is:
riant
'laughing' is the definition.
('riant' can be a synonym of 'laughing')
'scotsman in outskirts of rabat' is the wordplay.
'scotsman' becomes 'ian'.
'in' is an insertion indicator.
'outskirts of' means to remove the middle letters.
'rabat' with its centre removed is 'rt'.
'ian' placed into 'rt' is 'RIANT'.
(Other definitions for riant that I've seen before include "Laughing" , "patently amused" , "merry" .)