Suu, are clan banks basically just accounts created to store donations to clans?

Yes probably , but it can be use or something else

Mainly used for clan events

clan banks are to donate tc to there and the tc donated are used to every kind of clan events , like betting , tourneys , and some ways to duels also.

usually clan leader makes the bank account for example Nexus clan would have bank called BankNexus or NexusBank , got it?

This is good, so people won't send the tc to the owner, so it won't get mixed with the owner's tc and spend it on something.

I agree with Ginkey

The reason I asked is because members can't transfer TC if they have less than 20 QI, so if there was a way to simply withdrawal, that'd make sense, but I don't know.

the clan leader would have to get it up to atleast a blue belt to send money. well then there is more then 200qi