Pastry consumed by most rude Londoners (7)
I believe the answer is:
strudel
'pastry' is the definition.
(strudel is a kind of pastry)
'consumed by most rude londoners' is the wordplay.
'consumed by' indicates a hidden word (I've seen this in other clues).
'STRUDEL' is hidden in the letters of 'most rude londoners'.
(Other definitions for strudel that I've seen before include "A German baked pastry" , "German pie" , "Dessert of thin pastry filled with fruit" , "German fruit-filled pastry" , "Rolled pastry dessert" .)