Flatten out gold on layer with metal (7)
I believe the answer is:
plateau
'flatten out' is the definition.
(I've seen this in another clue)
'gold on layer with metal' is the wordplay.
'gold on layer' becomes 'plate' (I can't explain this - if you can you should believe this answer much more).
'with' says to put letters next to each other.
'metal' becomes 'Au' (Au is an example).
'plate'+'au'='PLATEAU'
Can you help me to learn more?
(Other definitions for plateau that I've seen before include "Elevated flatland" , "Area of flat, high ground" , "somewhere flatter?" , "relatively flat territory" , "hat" .)