Join a church following a tense time (6)
I believe the answer is:
attach
'join' is the definition.
(attaching is a kind of joining)
'a church following a tense time' is the wordplay.
'church' becomes 'ch' (common abbreviation**).
'following' says to put letters next to each other.
'tense' becomes 't' (abbreviation used in many dictionaries).
'time' becomes 't'.
'a'+'ch'='ach'
'a'+'t'+'t'='att'
'ach' after 'att' is 'ATTACH'.
(Other definitions for attach that I've seen before include "Join to something else" , "Secure" , "Add on to, couple" , "Bind, fasten" , "Conjoin, tie to" .)