New version of note welcomed by timeless band (5)
I believe the answer is:
remix
'timeless band' is the definition.
The definition suggests a verb in its base form which matches the answer.
'new version of note welcomed' is the wordplay.
'new version of' becomes 'rex' (I can't justify this - if you can you should give a lot more credence to this answer).
'note' becomes 'mi' (as in 'do re mi').
'welcomed' means one lot of letters goes inside another (inserted letters are welcomed in).
'rex' enclosing 'mi' is 'REMIX'.
'by' is the link.
Can you help me to learn more?
(Other definitions for remix that I've seen before include "Revised pop song" , "altered recording" , "Music produced by electronic alteration of tracks" , "Make a new version of a recording" , "Updated record" .)