Crossword Genius

Loosen a French item of furniture (8)

Ross

I believe the answer is:

unsettle

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'loosen' is the definition.
Although both the answer and definition are verbs in their base form, I don't understand how one could define the other.

'a french item of furniture' is the wordplay.
'a french' becomes 'un' ('a' in French).
'item of furniture' becomes 'settle' (I can't justify this - if you can you should believe this answer much more).
'un'+'settle'='UNSETTLE'

Can you help me to learn more?

(Other definitions for unsettle that I've seen before include "Upset" , "'Disturb, unnerve (8)'" , "Disturb, disconcert" , "Disturb, make anxious" , "Nettle us so as to disturb" .)

I've seen this clue in The Independent.
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