Rants about pet wandering in part of church (8)
I believe the answer is:
transept
'part of church' is the definition.
(I know this)
'rants about pet wandering' is the wordplay.
'about' indicates anagramming the letters.
'wandering' indicates an anagram.
'rants' with letters rearranged gives 'trans'.
'pet' anagrammed gives 'ept'.
'trans'+'ept'='TRANSEPT'
'in' acts as a link.
(Other definitions for transept that I've seen before include "Part of church intersecting nave" , "Side part of a church" , "Part of church off aisle" , "Patterns found in parts of church" , "Arm of church body" .)