Am all bent on backing the beast! (5)
I believe the answer is:
llama
'beast' is the definition.
(I've seen this before)
'am all bent on' is the wordplay.
'bent' is an anagram indicator.
'on' indicates putting letters inside (as in clothing 'on' a person).
'all' anagrammed gives 'lla'.
'am' going inside 'lla' is 'LLAMA'.
'backing the' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for llama that I've seen before include "Camel-like wool source" , "As bearer of burdens" , "Load-carrier" , "Fleecy mammal" , "Andean pack animal" .)