Instrument doctor’s used to probe a von Trapp (7)
I believe the answer is:
marimba
'instrument' is the definition.
(marimba is a kind of instrument)
'doctor's used to probe a von trapp' is the wordplay.
'doctor's used' becomes 'mb' (I can't explain this - if you can you should believe this answer much more).
'to probe' is an insertion indicator (probe can mean to poke or prod into).
'a von trapp' becomes 'maria' (I've seen this in another clue).
'mb' inserted inside 'maria' is 'MARIMBA'.
Can you help me to learn more?
(Other definitions for marimba that I've seen before include "Jazz instrument" , "Xylophone-like instr." , "Deep toned percussion instrument" , "Latin American instrument like a xylophone" , "African xylophone" .)