Things I tried for 21 before figuring it out
-My first guess was HYBRIDS because there are 7 hybrid flower collectibles but we all had lots of hybrids in our AC towns
-SNOWGLOBES because only 7 people own snowglobe collectibles
-Staff, tabs (there are 7 tabs on the menu bar), EGGHUNTS (which was on the right track but from the first clue I never would have guessed the answer was a number), fleas, turnips, bels, butterflyzippers, every TBT thing imaginable
-Pokemon, Yoshi, Pikmin, Chibirobo, every AC reference you could imagine
-Then I got really deep and started putting life things like nightmares, dreams, hopes, regrets, mistakes, tears, breakdowns...anything you can "have"
-Then I looked through every recent thread on TBT and put ones that had 7 posts or poll options that had 7 votes (I was particularly convinced about PANCAKES from a thread about favourite breakfast food because 7 people voted it and we all eat lots of pancakes)
Basically I wasted a whole lot of time yesterday before the clue was updated