Funny about 14d...I solved it, but was unsure of parsing because I'd forgotten that meaning of "quarrel" :-D ...there is a homophone of another meaning involved, but that one doesn't fully parse. Agreed on jono's parsing.
Re: 12D and the question of the penultimate letter - I think if it was intended to be "T" then the first two words of the clue would have been "bird-watchers", wouldn't it?
The jumbo cryptic in today's Observer (by Calypso) is not a prize one, which I assume is why it doesn't ask you to submit an email address on line. Curiously I can access the jumbo online, whereas I hit the paywall if I want to see the normal Everyman.
The short 10 seems to give a reverse signal-- Bear up -- which is not borne out by the solution. I get the regular letters from Guard's van, then Out of service -- what does this add?
And the distracting Up at the end.
I must be missing something.