US President popular, expelling extremists (3)
I believe the answer is:
ike
'us president' is the definition.
(nickname of Dwight Eisenhower)
'popular expelling extremists' is the wordplay.
'popular' becomes 'liked' (popular means well-liked).
'expelling extremists' means to look at the middle letters (letters on the extremes are removed).
The centre of 'liked' is 'IKE'.
(Other definitions for ike that I've seen before include "President Eisenhower" , "Thirty fourth US president's nickname" , "US general who became president, in short" , "Nickname for Dwight Eisenhower" , "Dwight D. Eisenhower, in short" .)