21a ancient persian capital I?f?h?n (7)
53d River depth reading So??sing (8)
73d Clover like plant A?a?is (6)
197a Docile horse P?l?r?? (7)
186d Sap used for arrack T?d?? (5)
21a ISFAHAN
53d SOUNDING (your ac. 's' is wrong, should be 'd')
not sure on 73d, ACACIA perhaps
197a PALFREY
don't know from arrack. Know what it tastes like, that's all.