Musical style reflected river and trees (3-3)

'musical style' is the definition.
(I've seen this before)

'reflected river and trees' is the wordplay.
'reflected' shows that the letters should be reversed in order (letters reflected back).
'river' becomes 'Po' (Italian river).
'and' means one lot of letters go next to another.
'trees' becomes 'wood'.
'po'+'wood'='powood'
'powood' reversed gives 'DOO-WOP'.