The scum cloak sais at the end if the turn roll a dice on a focus it goes away.

But if I have a focus token can I change it?

Basically...does this happen after cleanup phase? Or if a ship still has focus it can spend it to save the device?

You can't spend a Focus token to modify that die roll. The rule that lets you spend a Focus token to change all [eye]s to [boom]s is only relevant during the Modify Dice steps of an attack.

ETA: And even if you could, "At the end of the round" is after "during the End phase", so you have already cleaned up Focus and Evade tokens.

No, even with the Moldy crow title to let you keep Focus tokens, you can't spend the token to modify that die. If you look up "Focus" in the Rules Reference, you'll see that it only says you can spend Focus to change eyes to hits/evades "when attacking or defending". When you roll the Cloak card's check, you're not attacking or defending, so you can't spend Focus in that way.

Danke

You could technically Palp it in some weird mixed faction gameplay, thou.