Fellow feeling making them pay, possibly (7)
I believe the answer is:
empathy
'fellow feeling' is the definition.
(empathy is a kind of fellow feeling)
'them pay possibly' is the wordplay.
'possibly' indicates an anagram.
'them'+'pay'='thempay'
'thempay' anagrammed gives 'EMPATHY'.
'making' is the link.
(Other definitions for empathy that I've seen before include "Ability to identify mentally with another person" , "Psychological identification" , "Sharing experiences" , "Understanding" , "Shared emotion" .)