Admittedly, some of the mod ideas I have are for more than just clothing, but most of them are clothing. I've tried looking for some of these, but it looks like they aren't in the game. There's quite a few, so I'll just list them off.
-Starfleet Uniforms (It's kinda odd that there's mods for a phaser, but not uniforms. Plus it'd be pretty funny to equip a red shirt and melee weapon to some settlers.)
-Hairdo or wig to go with the Sailor Moon (I've been trying to find one that'd at least add a similar hairstyle as Usagi, but haven't found any. It's kinda odd that there isn't a Tuxedo Mask mod either, but I suppose I could make do with a Tuxedo, Oswald's Hat and Joker's mask from the Phantom Thief Mask mod.)
-Mario & Luigi clothing (It'd be kinda fitting to use that along with a flamethrower. A mod for the wig and dress of Peach, Daisy and Rosalina would be rather nice, too.)
-Gothic Lolita outfits
-Final Fantasy outfits (I know there's some already, but it seems like it's just a couple. They don't all have "Final Fantasy" in the title or description, so there's at least some that don't come up.)
-Natsu Dragneel (come to think of it, outfits of most of the characters from Fairy Tail would be pretty awesome. I am aware of there being a mod for Miliana's outfits though.)