Jazz man attending that school rings doctor (7)
I believe the answer is:
satchmo
'jazz man' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'attending that school rings doctor' is the wordplay.
'attending' becomes 'at' (e.g. at school means attending school).
'that school' becomes 'sch' (abbreviation).
'rings' is an insertion indicator (some letters are ringed or contained by others).
'doctor' becomes 'mo' (medical officer).
'at' inserted into 'sch' is 'satch'.
'satch'+'mo'='SATCHMO'
Can you help me to learn more?
(Other definitions for satchmo that I've seen before include "trumpeter" , "Louis Armstrong's byname" , "Louis Armstrong's nickname" , "Jazz musician" , "Name used by jazz player Louis Armstrong" .)