Steal into school sport inquiry (5)
I believe the answer is:
probe
'inquiry' is the definition.
(probe is a kind of inquiry)
'steal into school sport' is the wordplay.
'steal' becomes 'rob' (robbing is a kind of stealing).
'into' is an insertion indicator.
'school sport' becomes 'pe' (I am not sure about this - if you are sure you should believe this answer much more).
'rob' placed within 'pe' is 'PROBE'.
Can you help me to learn more?
(Other definitions for probe that I've seen before include "Inquiry" , "Spacecraft; investigation" , "Examine searchingly" , "Question or examine closely" , "sound" .)