Hi Warden, I also took ages to get 14d (it was my LOI) but it wasn't helped by the fact that I got the wrong tense (and hence the wrong letter) for 22a. I got it, once I realised my mistake, but still couldn't parse it. Jono's hints solved it for me. The 'fling' is of the throwing kind, that you might do at a fairground, if that helps.
I thought this was a fun, seasonal offering! Agree about 'greens' in 17a being a bit loose and tenuous. To use an American slang for cash to stand in for a British slang for cash, with no reference to the US? Bit odd. But overall, I thought it was very clever.
Happy Christmas all!