One who talks about exercising person in exchange (8)
I believe the answer is:
operator
'person in exchange' is the definition.
'operator' can be an answer for 'person' (operator is a kind of person). I'm not sure about the 'in exchange' bit.
'one who talks about exercising' is the wordplay.
'one who talks' becomes 'orator' (I can't explain this - if you can you should give a lot more credence to this answer).
'about' means one lot of letters goes inside another.
'exercising' becomes 'pe' (abbreviation for Physical Education).
'orator' placed around 'pe' is 'OPERATOR'.
Can you help me to learn more?
(Other definitions for operator that I've seen before include "Agent that handles an apparatus" , "Person who directs or controls, machine say (8)." , "Manipulative type of person" , "Driver" , "One working a machine" .)