I’d try to parse 17ac as a double definition &lit clue. We have two definitions of “damn”: “extremely minute”, corresponding to the definition in Chambers “something of little value”, and “nuts”, “an interjection expressing annoyance, disgust or impatience”. The wordplay is M (extremely indicates first letter of minute) + AND, with nuts indicating an anagram.
I realise that a lot of setters would not approve of using extremely to indicate a first letter, although some allow it for the first and last letters of a word. Also, extremely minute suggests an adjective, whereas something of little value is a noun.
But I suspect that Charybdis (and the editors) just didn’t check whether m was actually listed as an abbreviation for minute in Chambers - which gives “min.” as the abbreviation. A few setters would allow min to be read as m in, and “minute and nuts” as “M in AND*”, but I don’t think this is acceptable in The Listener Crossword.
By the way, the given name is in the list of some first names at the back of Chambers, so didn’t need to be referred to specifically in the preamble.