I found the bottom half pretty straightforward, but the top half FAR more difficult. Even so, after a while I thought I had filled in all the solutions but didn't understand the parsing of a few clues, so I zipped over to this forum for help. It turned out I had one filled in wrongly: I had a very common word, which could mean "commotion", as my solution for 4a, but couldn't figure out why "prince" meant "B". Now I know better. Two others I did get right, but needed help from this forum to fully parse; they were 10a and 11a. In 10a I should have realised what "for one" meant, because the same expression with the same meaning came in last Saturday's Guardian, and I understand it easily, but for some reason this time I didn't. Dunno why. I struggled with trying to parse 12a because I thought the 4th to 6th letters were the "trouble".
FOI 15a. LOI 4a. There were several contenders for COD, but I think I'll go for 25a.
On the whole I enjoyed this one.