More than 50 set on beast (4)
I believe the answer is:
lion
'beast' is the definition.
(type of animal)
'more than 50 set on' is the wordplay.
I cannot really see how this works, but
'50' could be 'l' (Roman numeral) and 'l' is found within the answer.
'on' is found in the answer.
A single letter 'i' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for lion that I've seen before include "Large cat; rugby player" , "British RU cap" , "Leo" , "Maned beast" , "Simba, for example" .)