... a large bundle, mostly put on a llama-like beast (6)
I believe the answer is:
alpaca
'a llama-like beast' is the definition.
(animal similar to the llama)
'a large bundle mostly put' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'bundle' becomes 'pack' (pack can mean a bundle of items).
'mostly' means to remove the last letter.
'put' becomes 'a' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'pack' with its final letter removed is 'pac'.
'a'+'l'+'pac'+'a'='ALPACA'
'on' acts as a link.
Can you help me to learn more?
(Other definitions for alpaca that I've seen before include "South American relative of the llama" , "(Woollen cloth from) relative of llama" , "S American animal related to llana" , "Llama-like animal with long black hair" , "S American mammal related to the llama" .)