Barnet fixer is hard character to control (8)

I believe the answer is:

hairgrip

'barnet fixer' is the definition.
(barnet can mean hair)

'hard character to control' is the wordplay.
'hard character' becomes 'hair' (I can't justify this - if you can you should give a lot more credence to this answer).
'to control' becomes 'grip' (grip is a kind of control).
'hair'+'grip'='HAIRGRIP'

'is' acts as a link.

(Another definition for hairgrip that I've seen is " one holding buns perhaps".)

I've seen this clue in The Times.

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