Remedy? Don't play guitar! (7)
I believe the answer is:
nostrum
'remedy?' is the definition.
(I know that nostrum is a type of remedy)
'don't play guitar' is the wordplay.
'don't' becomes 'no' (I can't explain this - if you can you should give a lot more credence to this answer).
'play guitar' becomes 'strum' (to strum is to play a guitar).
'no'+'strum'='NOSTRUM'
Can you help me to learn more?
(Other definitions for nostrum that I've seen before include "Must Ron take a quack remedy?" , "Favourite remedy or scheme" , "our Latin" , "Hypothetical remedy for all ills" , "Supposed remedy" .)