Meaning
A small worm or grub; also a firefly or glow-worm (Persian diminutive of kirm, worm).
Literally: Persian kirm (worm) plus the diminutive -ak.
How Iqbal uses it
In the verse the kirmak-e-shama, the little moth at the candle, speaks of an ancient ardour now missing from both poet's tale of burning and the candle's account of melting, a lament that the old intensity of love has faded.
See it in the verse