I too had trouble finding a good clove juice. I got some Dekang "Djarum" and that was ok, but very, very weak. So I got this idea to add some clove extract to it, but a quick check in the cupboard left me emptyhanded. But I did find some powdered ground clove, and set about my project which turned out pretty successfully!
1.) Put 3-4 tsp of powdered clove in a small pyrex custard cup
2.) Added vodka (smirnoff rail quality), about 1/4 cup to make a 'slurry'
3.) stirred well until slurry nice and brown
4.) folded 3 coffee filters over the mouth of a glass, poured slurry in
5.) wait until liquid filters through
6.) Emptied liquid to double boiler, heated to 180-200 deg fahrenheit (alcohol boils off at 173)
7.) Continue heating/reducing until liquid a dark brown, about 10 minutes.
8.) cool, bottle, etc.
This liquid added about 10% to the Djarum or 20% to DIY liquid is very clovey and reminds me of the old clove cigs you can't buy anymore. This is now my favorite all-day vape!