Cavity in heart needing attention (6,3)

I believe the answer is:

middle ear

'cavity' is the definition.
(cavity in the ear)

'heart needing attention' is the wordplay.
'heart' becomes 'middle' (synonyms).
'needing' says to put letters next to each other.
'attention' becomes 'ear' (having someone's ear is having their attention).
'middle'+'ear'='MIDDLE EAR'

'in' acts as a link.

(Another definition for middle ear that I've seen is " Where to find hammer".)

I've seen this clue in The Times.

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