Irritate English fellow retiring after tea (5)
I believe the answer is:
chafe
'irritate' is the definition.
(chafing is a kind of irritating)
'english fellow retiring after tea' is the wordplay.
'english' becomes 'E' (abbreviation).
'fellow' becomes 'F' (abbreviation - of a society etc.).
'retiring' says the letters should be written in reverse.
'after' says to put letters next to each other.
'tea' becomes 'cha' (cha is a type of tea).
'e'+'f'='ef'
'ef' reversed gives 'fe'.
'fe' after 'cha' is 'CHAFE'.
(Other definitions for chafe that I've seen before include "Rub abrasively" , "Wear away by rubbing" , "Rub annoyingly" , "Rub; become sore" , "Rub, irritate" .)