A Riley Rebus As Suggested By Duck

This is gonna be a Riley rebus suggested by @Duck (Thanks)
Be sure to check out some of his great riddles and puzzles like this and this :D

Note :

I will probably (Definitely) post another one of these. It's here :D

Will also add hints if nobody gets if after a while

Small Hint :

Don't take things too literally

Another Small Hint :

The Suffix picture is a game called agario

Specific Hint for Prefix :

It's a way of measuring something that is also related to a circle

Answer

Could it be something like

Radio?

Prefix

Rad (for radian)

Infix

di

Suffix

Io