Pack animal left Tibetan priest (5)
I believe the answer is:
llama
'pack animal' is the definition.
(I've seen this before)
'left tibetan priest' is the wordplay.
'left' becomes 'l' (common abbreviation).
'tibetan priest' becomes 'lama' (I've seen this before).
'l'+'lama'='LLAMA'
(Other definitions for llama that I've seen before include "Long-necked woolly animal" , "South-American cud-chewing animal" , "South American transport animal" , "one to chew the cud" , "Domesticated South American beast" .)