Oppressed ones put back science fiction thing in law (5)
I believe the answer is:
serfs
'oppressed ones' is the definition.
Although both the answer and definition are plural nouns, I cannot see how they can define each other.
'back science fiction thing in law' is the wordplay.
'back' says the letters should be written in reverse.
'science fiction' becomes 'SF' (abbreviation).
'thing in law' becomes 'res' (I've seen this in another clue).
'sf'+'res'='sfres'
'sfres' in reverse letter order is 'SERFS'.
'put' is the link.
Can you help me to learn more?
(Other definitions for serfs that I've seen before include "Farm labourers of Middle Ages" , "They were bound to work" , "Agricultural labourers tied to estate" , "They were owned by the feudal lord in the Middle Ages" , "Feudal labourers" .)