Loosen piece of hair after bun arranged (7)

I believe the answer is:

unblock

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'loosen piece' is the definition.
I can't tell whether this definition defines the answer.

'hair after bun arranged' is the wordplay.
'hair' becomes 'lock' (lock is a kind of hair).
'after' says to put letters next to each other.
'arranged' is an anagram indicator.
'bun' is an anagram of 'unb'.
'lock' put after 'unb' is 'UNBLOCK'.

'of' acts as a link.

Can you help me to learn more?

(Other definitions for unblock that I've seen before include "Remove an obstruction from" , "Clear (drains, etc)" .)

I've seen this clue in The Times.

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