Copy that is used by band famed saxophonist familiarly engages (10)
I believe the answer is:
transcribe
'copy that is used by band famed saxophonist familiarly engages' is the definition.
'transcribe' can be an answer for 'copy' (I've seen this before). I'm not sure about the rest of the definition.
'copy that is used by band' is the wordplay.
'copy' becomes 'crib' (crib can mean to copy from another source).
'that is used by' means one lot of letters goes inside another.
'band' becomes 'transe' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'crib' going inside 'transe' is 'TRANSCRIBE'.
Can you help me to learn more?
(Other definitions for transcribe that I've seen before include "Copy into another form" , "Copy out longhand" , "write up" , "Take down" .)