American, on reflection, providing entertainment (7)
I believe the answer is:
amusing
'providing entertainment' is the definition.
(I've seen this before)
'american on reflection' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'on' says to put letters next to each other.
'reflection' becomes 'musing' (synonyms).
'a'+'musing'='AMUSING'
(Other definitions for amusing that I've seen before include "Humorous" , "Droll" , "Entertaining, pleasing" , "Pleasantly diverting" , "Mildly funny - diverting" .)