Does it securely fasten curled hair to head?

I believe the answer is:

lock nut

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'does it securely fasten curled' is the definition.
I can't tell whether this definition defines the answer.

'hair to head?' is the wordplay.
'hair' becomes 'lock' (lock is a kind of hair).
'to head?' becomes 'nut' (informal term for somebody's head).
'lock'+'nut'='LOCK-NUT'

Can you help me to learn more?

(Other definitions for lock nut that I've seen before include "Safety device on a bolt" , "Threaded fastener" , "Screw-fastening device" , "Bolt's extra securer" , "What stops a bolt coming undone" .)

I've seen this clue in The Telegraph.

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