By introducing it, church is vindictive (6)
I believe the answer is:
bitchy
'vindictive' is the definition.
Both the answer and definition are adjectives. Maybe they are linked in a way I don't understand?
'by introducing it church' is the wordplay.
'introducing' is an insertion indicator (some letters introduced or inserted into others).
'church' becomes 'ch' (common abbreviation).
'it'+'ch'='itch'
'by' going around 'itch' is 'BITCHY'.
'is' is the link.
Can you help me to learn more?
(Other definitions for bitchy that I've seen before include "malicious" , "Unpleasant and spiteful like female dog" , "Catty" , "Speaking spitefully in manner of female canine" .)