I had a similar doh moment when I parsed it. I’d had it pencilled in for ages. I was trying to make it fit a word meaning cut going backwards, rather than cutting a word meaning back. A nice trap set by Nutmeg... clever clueing.
Very good puzzle from a setter whose clues are always meticulously fair. Having said that I have actually been unable to parse 10d, which has perplexed two other posters without yet having been fully explained. Clearly the def is 'trumpet', and back-tracking from the final solve confirms A as the omitted letter ... so how does the business with the hands work?