Note that comes and goes (5)
I believe the answer is:
minim
'note that comes and goes' is the definition.
'minim' can be an answer for 'note' (musical note). I'm not sure about the rest of the definition.
'note that comes and goes' is the wordplay.
'note' becomes 'mi' (as in 'do re mi').
'that comes and goes' becomes 'nim' (I can't justify this - if you can you should give a lot more credence to this answer).
'mi'+'nim'='MINIM'
Can you help me to learn more?
(Other definitions for minim that I've seen before include "Double crotchet" , "Palindromic note" , "Half-semibreve" , "Short note" , "Quarter of a breve" .)