Not totally exposed, back part of organ (5,3)

I believe the answer is:

outer ear

'part of organ' is the definition.
(the ear is an organ)

'not totally exposed back' is the wordplay.
'not totally' means to remove the last letter.
'exposed' becomes 'outed' (to out someone is to expose them).
'back' becomes 'rear' (something's rear is its back).
'outed' with its final letter taken off is 'oute'.
'oute'+'rear'='OUTER EAR'

(Another definition for outer ear that I've seen is " External part of human auditory organ".)

I've seen this clue in The Telegraph.

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