Big Persian magnate? (3,3)
I believe the answer is:
fat cat
'magnate?' is the definition.
(I've seen this before)
'big persian' is the wordplay.
'big' becomes 'fat'.
'persian' becomes 'cat' (Persian is a type of cat).
'fat'+'cat'='FAT-CAT'
(Other definitions for fat cat that I've seen before include "Banking executive maybe" , "Magnate" , "Influential politician" , "Derogatory term for wealthy person" , "Wealthy person like obese feline" .)