Great runner has run off after felon (5)
I believe the answer is:
congo
'great runner' is the definition.
'congo' can be an answer for 'runner' (Congo is an example). I am not sure about the 'great' bit.
'run off after felon' is the wordplay.
'run off' becomes 'go' (both can mean to function or work. I am not sure about the 'off' bit.).
'after' says to put letters next to each other.
'felon' becomes 'con' (abbreviation for 'convict').
'go' put after 'con' is 'CONGO'.
'has' is the link.
Can you help me to learn more?
(Other definitions for congo that I've seen before include "It was known as Zaire" , "African river (aka Zaire)" , "African river and region" , "Region of central Africa" , "African republic" .)