Cop pins arm roughly in place of captivity (6,4)
I believe the answer is:
prison camp
'place of captivity' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'cop pins arm roughly' is the wordplay.
'roughly' is an anagram indicator.
'cop'+'pins'+'arm'='coppinsarm'
'coppinsarm' is an anagram of 'PRISON CAMP'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for prison camp that I've seen before include "Stalag perhaps" , "gulag" .)