Revolutionise karaoke to collect rising gains (5,2)
I believe the answer is:
rakes in
'gains' is the definition.
(raking in is a kind of gaining)
'revolutionise karaoke to collect rising' is the wordplay.
'to collect' says the answer is hidden in the clue.
'rising' shows that the letters should be reversed in order (going up in a down clue).
'nisekar' can be found hidden inside 'revolutionise karaoke'.
'nisekar' reversed gives 'RAKES IN'.
(Other definitions for rakes in that I've seen before include "makes a lot of money" , "earns large amounts" , "gets paid" , "profits quickly" .)