Steps governor advanced with river rising (5,4)
I believe the answer is:
bossa nova
'steps' is the definition.
(I've seen this before)
'governor advanced with river rising' is the wordplay.
'governor' becomes 'boss' (I've seen this before).
'advanced' becomes 'a' (abbreviation).
'with' is a charade indicator (letters next to each other).
'river rising' becomes 'nova' (I can't justify this - if you can you should give a lot more credence to this answer).
'boss'+'a'+'nova'='BOSSA NOVA'
Can you help me to learn more?
(Other definitions for bossa nova that I've seen before include "(Music for) a Brazilian dance" , "steps taken" , "lively dance" , "Dance from Brazil similar to samba" , "Brazilian music, rhythmically related to the samba" .)