A thoughtful comic (7)
I believe the answer is:
amusing
'comic' is the definition.
(I've seen this before)
'a thoughtful' is the wordplay.
'thoughtful' becomes 'musing' (similar in meaning).
'a'+'musing'='AMUSING'
(Other definitions for amusing that I've seen before include "Comical" , "Droll" , "Entertaining, diverting" , "Humorous" , "Providing entertainment" .)