Hi, anybody know the meaning of the radical in the lower right section of "夜"? Is it even a radical at all?

It is basically "夂" with a dot in the middle.

Thanks!

It isn't a radical. There is 夂 and 夕.

I see.

Thanks.

夜 is the combination of a modified 亦 and 夕. In the modification, the 4th stroke of 亦 is lost and the final stroke is combined with 夕. So the component in the lower right is 夕 + the final stroke of 亦. This 夜 character carries the message, “I'm 'also' a 夕, but read like a 亦.” Broadly speaking, 夜 and 夕 have similar meaning, though there are minor differences. The final stroke of 亦 is added to 夕 to make it looks more like a 月. This emphasizes that 夜 concerns more with the period when the moon rules, that is the whole night, in contrast with 夕 which is half a moon and means evening.