If she’s a big girl I’d look for something a little bigger than 1” just so long as it’s still an unsexed juvenile. Sometimes the females can be a bit rough on the real little guys. Also if she doesn’t play nice you can put her in the acclimation box, kind of a sort of time out so that the new guy can get accustomed to the new tank without being overly hassled. It’s her tank right now so she might be a bit territorial, removing her to the acclimation box will help with that. Just make sure you keep a close eye on them and be ready to remove one or the other if it gets too bad. What kind of clown?