A long way off getting a return of service (4)
I believe the answer is:
'a long way off' is the definition.
(I've seen this before)
'a return of service' is the wordplay.
'return of' shows that the letters should be reversed in order.
'service' becomes 'raf'.
'raf' written backwards gives 'far'.
'getting' is the link.
(Other definitions for afar that I've seen before include "a good way off" , "Unusually distant" , "Many a mile" , "Not in this neighbourhood" , "from baseline to baseline?" .)