Religious leader Father essentially reveres (4)
I believe the answer is:
pope
'religious leader' is the definition.
(I've seen this in another clue)
'father essentially reveres' is the wordplay.
'father' becomes 'pop' (pop is a kind of father).
'essentially' indicates the central letters.
The centre of 'reveres' is 'e'.
'pop'+'e'='POPE'
(Other definitions for pope that I've seen before include "church leader in Rome" , "Well-versed man" , "Head of RC church" , "served in the Vatican" , "English poet, d. 1744" .)