I too suspect a mistake. Po(-faced) for wooden is conceivable, but doesn’t really fit with the clue construction. They used to be made of wood, so i think the setter just messed up his anagram
I used to buy the RT every week and enjoyed the cryptic crossword.
However, the setters changed, the clues often had mistakes and I finally stopped buying.
The situation appears not to have improved
Thank you one and all!
I now don't feel as dim as I thought!
Perhaps the setter should come on here and explain it him/herself and put us all out of our misery