US President, loser with vote collapsing (9)
I believe the answer is:
roosevelt
'us president' is the definition.
(Theodore Roosevelt or Franklin Delano Roosevelt)
'loser with vote collapsing' is the wordplay.
'with' means one lot of letters go next to another.
'collapsing' is an anagram indicator.
'loser' after 'vote' is 'voteloser'.
'voteloser' is an anagram of 'ROOSEVELT'.
(Other definitions for roosevelt that I've seen before include "Leading statesman in war" , "See president" , "Old president" , "One of two US presidents" , "former president" .)