Old pen carried upside down by Mozart, a classicist (8)

I believe the answer is:

alcatraz

I'm a little stuck... Click here to teach me more about this clue!

'old pen' is the definition.
'alcatraz' can be an answer for 'pen' (I've seen this before). I'm not sure about the 'old' bit.

'carried upside down by mozart a classicist' is the wordplay.
'upside down' says the letters should be written in reverse.
'carried' says the answer is hidden in the clue.
'zartacla' can be found hidden inside 'by mozart a classicist'.
'zartacla' back-to-front is 'ALCATRAZ'.

Can you help me to learn more?

(Other definitions for alcatraz that I've seen before include "Old Calif. offshore prison" , "Pen" , "Californian island" , "old US jail" , "(Former prison) island in San Francisco Bay" .)

I've seen this clue in The Telegraph.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.