Undertaking talk about school sport (9)
I believe the answer is:
operation
'undertaking' is the definition.
(I've seen this before)
'talk about school sport' is the wordplay.
'talk' becomes 'oration' (I've seen this in another clue).
'about' indicates putting letters inside.
'school sport' becomes 'pe' (I am not sure about this - if you are sure you should believe this answer much more).
'oration' going around 'pe' is 'OPERATION'.
Can you help me to learn more?
(Other definitions for operation that I've seen before include "medical treatment" , "battle" , "Surgical or military procedure" , "working" , "financial transaction" .)