Rebellious figure completely hidden in fen with a northern set (6,5)
I believe the answer is:
fallen angel
'rebellious figure' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'completely hidden in fen with a northern set' is the wordplay.
'completely' becomes 'all' (synonyms).
'hidden in' is an insertion indicator.
'with' says to put letters next to each other.
'a' becomes 'an'.
'northern set' becomes 'gel' (both can mean to harden. I am not sure about the 'northern' bit.).
'all' inserted inside 'fen' is 'fallen'.
'fallen'+'an'+'gel'='FALLEN ANGEL'
Can you help me to learn more?
(Other definitions for fallen angel that I've seen before include "Rebel against God" , "Devil" , "Former resident of heaven?" , "Rebel spirit from heaven" , "outcast" .)