Diagram of plans from Persian Gulf (6)
I believe the answer is:
figure
'diagram' is the definition.
(thesaurus)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for figure that I've seen before include "The written symbol of a number" , "Statistic - physique" , "form" , "Judge to be probable, estimate" , "Build" .)