Not steady like a furniture item (7)

I believe the answer is:

astable

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'not steady like a furniture item' is the definition.
I can't tell whether this defines the answer.

'like a furniture item' is the wordplay.
'like' becomes 'as'.
'a furniture item' becomes 'table' (I've seen this before).
'as'+'table'='ASTABLE'

Can you help me to learn more?

I've seen this clue in The Irish Independent.

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