One has a beastly laugh and a hearty desire (5)
I believe the answer is:
hyena
'a hearty desire' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'one has a beastly laugh and' is the wordplay.
I cannot really understand how this works, but
'one' could be 'a' and 'a' is present in the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is found in the answer.
The remaining letters 'hye' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for hyena that I've seen before include "African scavenger" , "Dog-like African carnivore" , "he's a laugh" , "Scavenging animal" , "Scavenging carnivore" .)