Having turned up with Mozart, a clarinettist is entertaining captives there (8)
I believe the answer is:
alcatraz
'entertaining captives there' is the definition.
I can't tell whether this definition defines the answer.
'having turned up with mozart a clarinettist' is the wordplay.
'having turned up' says the letters should be written in reverse.
'with' indicates a hidden word.
'zartacla' is hidden in the letters of 'mozart a clarinettist'.
'zartacla' back-to-front is 'ALCATRAZ'.
'is' is the link.
Can you help me to learn more?
(Other definitions for alcatraz that I've seen before include "Old Calif. offshore prison" , "Island in San Francisco Bay,once a prison" , "(Former prison) island in San Francisco Bay" , "old US jail" , "Pen" .)