I agree but didn't know how to phrase it without spoiling the puzzle for others. It would be really pushing boundaries if ???u met the definition even if it is used for skirting boards !
I am now even more puzzled than usual given the comments about 29a. I have an alternative spelling for an Arab prince written backwards but I think 'skirts' is the definition and is a simple plural ending in 's'. I am really struggling with 3 down ( plod on building bypass - 6/two words) and 30 down (quaintly quondam lyric about what gets love going - 4). I think the third letter of that clashes with the last letter of 34 across. Any pointers would be greatly appreciated.
Mysteriously the on-line clue for 29A now has "Tree" as its first word. I'm guessing Chris is reading this (Hi, Chris!) and that a late emendation has been included. Will all paper copies of the ST be gathered in and pulped? Watch this space!