Underworld figure caught traitor and capitalist (9)
I believe the answer is:
plutocrat
'capitalist' is the definition.
(a plutocrat derives power from wealth)
'underworld figure caught traitor' is the wordplay.
'underworld figure' becomes 'pluto' (I've seen this in another clue).
'caught' becomes 'c' (cricket abbreviation).
'traitor' becomes 'rat' (I've seen this before).
'pluto'+'c'+'rat'='PLUTOCRAT'
'and' is the link.
(Other definitions for plutocrat that I've seen before include "Richest man" , "One powerful through wealth" , "One rich and powerful" , "One who's power derives from wealth" , "one wealthy" .)