Father goes to the east as a religious leader (4)
I believe the answer is:
pope
'a religious leader' is the definition.
(I've seen this in another clue)
'father goes to the east' is the wordplay.
'father' becomes 'pop' (pop is a kind of father).
'goes to' means one lot of letters go next to another.
'the east' becomes 'E' (abbreviation).
'pop'+'e'='POPE'
'as' acts as a link.
(Other definitions for pope that I've seen before include "Francis < Alexander" , "Satirist" , "Catholic leader" , "Bishop of Rome" , "John, Paul or Adrian, perhaps?" .)