See through the French and the heartless Normans. (4)
I believe the answer is:
lens
'see' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'the french and the heartless normans' is the wordplay.
'the french' becomes 'le' ('the' in French).
'and' says to put letters next to each other.
'the heartless' says to hollow out the word (remove centre letters).
'normans' with its centre removed is 'ns'.
'le'+'ns'='LENS'
'through' acts as a link.
Can you help me to learn more?
(Other definitions for lens that I've seen before include "Piece of glass, usually curved" , "town in France" , "Focussing device" , "One could project a picture" , "Bit of a looker" .)