A rook sang about marsupials (9)

I believe the answer is:

kangaroos

'marsupials' is the definition.
(I know that kangaroo is a type of marsupials)

'a rook sang about' is the wordplay.
'about' indicates anagramming the letters.
'a'+'rook'+'sang'='arooksang'
'arooksang' is an anagram of 'KANGAROOS'.

(Another definition for kangaroos that I've seen is " Large leaping mammals".)

I've seen this clue in The Independent.

Want a hint initially instead of a full solution? Install my app