From Hades, guilty criminal, first bum to make unwelcome appearance (4,3,4,4)

I believe the answer is:

rear its ugly head

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'bum to make unwelcome appearance' is the definition.
I don't know anything about this answer so I cannot judge whether this works.

'from hades guilty criminal' is the wordplay.
'from' becomes 'rear' (I can't explain this - if you can you should believe this answer much more).
'criminal' indicates anagramming the letters.
'hades'+'guilty'='hadesguilty'
'hadesguilty' anagrammed gives 'itsuglyhead'.
'rear'+'itsuglyhead'='REAR ITS UGLY HEAD'

'first' acts as a link.

Can you help me to learn more?

I've seen this clue in The Guardian.

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