Farewell in church always one associated with love (7)
I believe the answer is:
cheerio
'farewell' is the definition.
(I know that cheerio is a type of farewell)
'church always one associated with love' is the wordplay.
'church' becomes 'ch' (common abbreviation).
'always' becomes 'eer' (poetic way of saying ever).
'one' becomes 'i' (Roman numeral).
'associated with' says to put letters next to each other.
'love' becomes 'o' (love means zero in tennis).
'ch'+'eer'+'i'+'o'='CHEERIO'
'in' is the link.
(Other definitions for cheerio that I've seen before include "See you" , "Expression used when leaving" , "A final word" , "Bye" , "British romance imprint" .)