So angry about agent coming back with terms for another Harry Potter (7,5)

I believe the answer is:

grayson perry

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'another harry potter' is the definition.
I don't know anything about this answer so I cannot judge whether this works.

'so angry about agent coming back with terms' is the wordplay.
'about' indicates an anagram.
'agent' becomes 'rep' (short for representative).
'coming back' says the letters should be written backwards.
'with' is a charade indicator (letters next to each other).
'terms' becomes 'ry' (I can't justify this - if you can you should believe this answer much more).
'rep' back-to-front is 'per'.
'so'+'angry'='soangry'
'soangry' with letters rearranged gives 'grayson'.
'grayson'+'per'+'ry'='GRAYSON PERRY'

'for' acts as a link.

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I've seen this clue in The Independent.

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