Some have delusions of this German currency dominating another mostly (8)
I believe the answer is:
grandeur
'some have delusions of this german' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'currency dominating another mostly' is the wordplay.
I cannot really see how this works, but
'currency' could be 'rand' (I've seen this before) and 'rand' is located in the answer.
'another' could be 'r' (I've seen this in other clues) and 'r' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for grandeur that I've seen before include "Pomp" , "Majesty - eminence" , "state" , "Impressiveness of appearance" , "Majesty (God's, Hopkins)" .)