I initially found this very difficult, but then I solved a particular clue in the SW and things started to click in to place.
Geeker, I did wonder if you might struggle, as I know you don't have a copy of Chambers, but then I realised what a ridiculous notion that was given the myriad of other resources available. I think this cruciverbalist's malady of ROC (reliance on Chambers) is at risk of reaching epidemic proportions!
A couple of parsing issues:-
12a - I can see a "flight" (not 'flights' plural) followed by an "author" but can't see a definition and am at a loss to explain "they cover" and "in a flurry".
16d - I can't help but feel this should begin with either "signal agreement" or "sign of an agreement" rather than "sign agreement", which just looks and sounds wrong.
Now, in 99% of cases where I think something is amiss the error is mine, so I look forward to some more erudite solver showing me the error of my ways:-)
Thanks to Brendan for a very clever and well constructed puzzle and one which pays back the solver's perseverance back in spades.
How did you all get on - did you find it as tricky as me or was it more the proverbial walk in the park?
Leave a post letting us know how you fared and, as always, if you do run into difficulties, just post your query on here.
Stay safe:-)