On which to speak, or possibly play guitar (7)
I believe the answer is:
rostrum
'on which to speak' is the definition.
I can't judge whether this defines the answer.
'or possibly play guitar' is the wordplay.
'possibly' indicates an anagram.
'play guitar' becomes 'strum' (to strum is to play a guitar).
'or' with letters rearranged gives 'ro'.
'ro'+'strum'='ROSTRUM'
Can you help me to learn more?
(Other definitions for rostrum that I've seen before include "place for speaker" , "Platform for public speaking" , "stage" , "Platform for speaker" , "beak" .)