Erstwhile queen lost crumpled suit in the East End (7)
I believe the answer is:
whistle
'suit in the east end' is the definition.
'whistle' can be an answer for 'suit' (I've seen this before). I'm unsure of the 'in the east end' bit.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for whistle that I've seen before include "sound surprised" , "He wilts (anag.)" , "Pucker up and blow" , "L.S.White (anag.)" , "Shrill piping sound" .)