Struggle to get iron into thin layer (5)
I believe the answer is:
wafer
'thin layer' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'struggle to get iron' is the wordplay.
'struggle' becomes 'war' (warring is a kind of struggling).
'to get' means one lot of letters goes inside another.
'iron' becomes 'Fe' (chemical symbol for iron).
'war' going around 'fe' is 'WAFER'.
'into' is the link.
Can you help me to learn more?
(Other definitions for wafer that I've seen before include "thin stuff" , "Communion bread" , "Disc of bread" , "Ice cream biscuit" , "Very thin slice" .)