Member of upper house maintaining backing for appeal gets cash in (9)
I believe the answer is:
profiteer
'cash in' is the definition.
'member of upper house maintaining backing for appeal' is the wordplay.
'member of upper house' becomes 'peer' (member of the House of Lords).
'maintaining' is an insertion indicator.
'backing' is a reversal indicator.
'appeal' becomes 'it'.
'for' written backwards gives 'rof'.
'rof'+'it'='rofit'
'peer' placed around 'rofit' is 'PROFITEER'.
'gets' is the link.
(Other definitions for profiteer that I've seen before include "Make excessive gains" , "One making excessive gains from trading" , "financial exploiter" , "One charging too much" , "capitalist" .)