Very much enjoyed this Everyman and has others have mentioned, it continues a fine run. I also got hung up over a headless rodent in 16d (first 5 letters reversed). There’s also another headless weaselly type in the bottom 5 letters reversed… add an r for that one, so thanks to this thread for the correct parsing.
According to the Uxbridge English Dictionary which is regularly dipped into on I’m Sorry I Haven’t A Clue, 3d can also mean “the angle at which a thermometer is inserted.”