One's upset, after church, to be selected (6)
I believe the answer is:
chosen
'be selected' is the definition.
(similar in meaning)
'one's upset after church' is the wordplay.
'upset' indicates an anagram.
'after' says to put letters next to each other.
'church' becomes 'ch' (common abbreviation).
'ones' anagrammed gives 'osen'.
'osen' put after 'ch' is 'CHOSEN'.
'to' acts as a link.
(Other definitions for chosen that I've seen before include "Select" , "'''Many are called, but few are ...'' (Bible) (6)'" , "Elected, picked" , "part of Asia once" , "If you're one of these few, you're very privileged" .)