Thanks, Buzzybee. My Shorter/big dictionary was closer to hand, so I looked in there first - and checked Chambers later as you'd mentioned it. It's not the best of clues!
Jono, your parsing of 25 A makes it a little better, a little more valid,than I thought. I felt the puzzle was too light, too slight to be classed as 'good' - I'd have welcomed more of a challenge.