Hard currency advanced to scavenger (5)
I believe the answer is:
hyena
'to scavenger' is the definition.
(animal which scavenges)
'hard currency advanced' is the wordplay.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'currency' becomes 'yen' (Japanese currency).
'advanced' becomes 'a' (abbreviation).
'h'+'yen'+'a'='HYENA'
(Other definitions for hyena that I've seen before include "Dog-like carrion-feeding mammal" , "Spotted scavenger" , "Wild mammal" , "Scavenging carnivore" , "Laughing mammal?" .)