Why did minjae clench his fist?

Jealousy

He’s jealous

see i asked cause i thought he was annoyed their date got interrupted and or annoyed hes gonna contact his connections to help jiyong (this js just a guess) so thanks for that!

I thought he saw Heechan smile and he was holding himself back from pouncing him.... at least that's how it usually goes in BLs

actually i think i prefer this theory

I got the same impression

Yeah he wants to FUCK

Definitely this is the reason. He holds back really hard