Capitalist rating business: union record on the up (9)
I believe the answer is:
plutocrat
'capitalist' is the definition.
(a plutocrat derives power from wealth)
'rating business union record on the up' is the wordplay.
'rating' becomes 'tar' (both can mean a sailor).
'business' becomes 'co' (short for company).
'union' becomes 'tu' (abbreviation for trade union).
'record' becomes 'LP' (abbreviation for long play record).
'on the up' shows that the letters should be reversed in order (in a down clue, letters go up).
'tar'+'co'+'tu'+'lp'='tarcotulp'
'tarcotulp' in reverse letter order is 'PLUTOCRAT'.
(Other definitions for plutocrat that I've seen before include "powerful rich type" , "One powerful through wealth" , "Magnate" , "Wealthy man" , "Powerful rich man" .)