Second clown?

[Delphinus]

Short answer is you can probably get another. Whether they pair up again depends on how you play your cards though.

The best bet, IMO, is to get one that is considerably smaller than your existing fish. This is will "encourage" submission to the existing fish, and then they should get along. The larger fish, if not already a female will become the female (and even if it was the male before, given that it's been on its own for a month, given the absence of a dominant female, could be on the verge of transitioning from male to female).

If you get another similarly sized fish you likely will see a lot of fighting. If both are males, they will "fight for the right to become female". If they are both female, likely they will fight forever for territory. (Once female, you don't go back down to being male.)

When I've lost a fish in my pairing, this is how I would introduce a new one (ie., pick one that is way smaller). This happened to me two times, ie., losing one fish of the pairing, and each time eventually resulted in a mated pairing with former male becoming female, and the newcomer becoming the male.

HTH!