Backing some Arabian oil limits big figure (7)
I believe the answer is:
million
'big figure' is the definition.
The answer and definition can be both quantities as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'backing some arabian oil limits' is the wordplay.
'backing' is a reversal indicator.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'noillim' is hidden within 'arabian oil limits'.
'noillim' backwards is 'MILLION'.
Can you help me to learn more?
(Other definitions for million that I've seen before include "One followed by six zeros" , "fortune!" , "Ten thousand hundreds" , "Large number" , "A power of 1 Down" .)