President's first lady left in sleeping-place (9)
I believe the answer is:
roosevelt
'president's' is the definition.
(Roosevelt is an example)
'first lady left in sleeping-place' is the wordplay.
'first lady' becomes 'eve' (I've seen this before).
'left' becomes 'l' (common abbreviation).
'in' is an insertion indicator.
'sleeping-place' becomes 'roost' (I've seen this before).
'eve'+'l'='evel'
'evel' placed into 'roost' is 'ROOSEVELT'.
(Other definitions for roosevelt that I've seen before include "former president" , "One of two US presidents" , "Leading statesman in war" , "Long-term leader" , "Teddy" .)