Unlikely to be outwitted or feel pain (5)
I believe the answer is:
smart
'feel pain' is the definition.
(thesaurus)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for smart that I've seen before include "Well-dressed" , "Trams (anag.)" , "Quick - trim" , "Posh" , "Intelligent; sting" .)