15d Unusual genius I left taking in new, endlessly showy room with light? (3,6)
An anagram (unusual) of genus (genius, I left) around (taking in) n(ew) + lou(d) (endlessly showy)
19d (not 18d) Pay separately a lot of tax with companion after work (2,5)
Go (work) + dut(y) (a lot of tax) + CH (Companion of Honour)
24d Muslim leader reported damaging blow (5)
Shake (damaging blow � a bit over the top?) � sounds like (reported) Sheikh (Muslim leader)