The most common and most likely answer to this crossword clue is the 8 letter word OTOSCOPE
I've seen this crossword clue in The Guardian
O
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More clues leading to the result OTOSCOPE
- Lug instrument and books round room
- Inspection kit is redundant, but not one containing catch
- I wish I could manage to hold small lighter in canal
- If only I could manage to hold small probe
- Books room full of old equipment for a medical exam
- Some photos cop exhibited considered instrumental in hearing
- Hearing instrument and compass fitted to centre of car
- Starting over, the ophthalmic surgeons manage to get the wrong instrument!
- Manage to support upended drunk after initially obtaining medical device
- Occupational therapists inhale oxygen, then manage a medical instrument
Buddy explains!

The straight part
We know that "the wrong instrument" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the wrong instrument = otoscope.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does OTOSCOPE mean?
OTOSCOPE noun- An instrument used for examining the eardrum and interior of the outer ear.