Catty in past about Italian church (6)
I believe the answer is:
bitchy
'catty' is the definition.
('bitchy' can be a synonym of 'catty')
'past about italian church' is the wordplay.
'past' becomes 'by' ('by' can be a synonym of 'past').
'about' means one lot of letters goes inside another.
'italian' becomes 'it'.
'church' becomes 'ch' (common abbreviation).
'it'+'ch'='itch'
'by' enclosing 'itch' is 'BITCHY'.
'in' is the link.
(Other definitions for bitchy that I've seen before include "Unpleasant and spiteful like female dog" , "Speaking spitefully in manner of female canine" , "malicious" , "Catty" .)