Roman unfortunately loses right to complain (4)
I believe the answer is:
moan
'complain' is the definition.
(moan can mean to complain or whinge)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for moan that I've seen before include "Expression of suffering" , "Complaint" , "Complain, groan" , "Bewail" , "Indicate pain" .)