Boo when lord ditches Penny for Juliet (4)
I believe the answer is:
jeer
'boo' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for jeer that I've seen before include "Catcall" , "Tease" , "Mock publicly" , "Boo" , "Barrack" .)