Hi @alison11,
Great question!
I haven’t cut a candle myself so I can’t say for sure, but I can see how it would work in theory. It might be a little tricky getting the bottom half to start, but if you hold the flame close and let the wax burn away to reveal the wick, it might be okay and catch on.
I second what @Ostara said about using birthday candles instead- they are great for short-term spells! Another option is to use chime candles (sometimes listed as “spell candles” on witchy sites and marketplaces). Tealight candles are small too- and have the extra bonus of already coming in a holder.
Another option is to respectfully snuff the candle when you are done with your spell. While there are many witches who wait for the candle to extinguish on its own, there are also many witches who extinguish and reuse candles- here’s a great discussion about resuing spell candles where you might get some ideas and inspiration- at the end of the day, it’s up to you to find what works best for you and your practice! 
Wishing you a blessed full moon- happy spellwork, Alison! 