After radio ends, play guitar on stage (7)
I believe the answer is:
rostrum
'stage' is the definition.
(I've seen this before)
'after radio ends play guitar' is the wordplay.
'ends' indicates one should take the final letters.
'play guitar' becomes 'strum' (I've seen this before).
The last letters of 'after radio' are 'ro'.
'ro'+'strum'='ROSTRUM'
'on' acts as a link.
(Other definitions for rostrum that I've seen before include "Podium" , "Platform for public speakers" , "Rum rots (anag)" , "Platform for orchestra conductor" , "Platform for public speaking" .)