I married a couple in cleric's office (7)
I believe the answer is:
imamate
'cleric's office' is the definition.
(I've seen this before)
'i married a couple in' is the wordplay.
'married' becomes 'm' (abbreviation, e.g. in genealogy).
'couple' becomes 'mate' (synonyms).
'in' means one lot of letters goes inside another.
'm'+'a'='ma'
'ma' put within 'mate' is 'mamate'.
'i'+'mamate'='IMAMATE'
(Other definitions for imamate that I've seen before include "Imam's jurisdiction" , "cleric's office" , "part of Moslem world" , "Muslim leader's office" , "position of Muslim leader" .)