Aggregate that is without nitrogen in gold both ways (4,3)
I believe the answer is:
iron ore
'nitrogen in gold both ways' is the definition.
The answer and definition can be both substances as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'aggregate that is without' is the wordplay.
I cannot quite understand how this works, but
'aggregate' could be 'ore' (I've seen this before) and 'ore' is located in the answer.
The remaining letters 'iron' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for iron ore that I've seen before include "Metal-yielding mineral" , "Useful mineral" , "Rock from which a metal can be extracted" , "Material containing ferric metal" , "Metal-bearing mineral" .)