It's beaten by those who are themselves beaten (7)
I believe the answer is:
retreat
'it's beaten by those' is the definition.
I can't judge whether this definition defines the answer.
'are themselves beaten' is the wordplay.
I cannot really see how this works, but
an anagram of 'are' is 'rea' which is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'who' is the link.
Can you help me to learn more?
(Other definitions for retreat that I've seen before include "Back away" , "concession" , "place for meditation" , "Give ground" , "Monastery - bugle call" .)