Bird, variegated sort one's seen on church (7)
I believe the answer is:
ostrich
'bird' is the definition.
(ostrich is a kind of bird)
'variegated sort one's seen on church' is the wordplay.
'variegated' indicates an anagram.
'one' becomes 'i' (Roman numeral).
'seen on' is a charade indicator (letters next to each other).
'church' becomes 'ch' (common abbreviation).
'sort' with letters rearranged gives 'ostr'.
'ostr'+'i'+'ch'='OSTRICH'
(Other definitions for ostrich that I've seen before include "The head-in-the-sand bird" , "Fast winger" , "Rich sot seeks large bird" , "A bird for the shirt co." , "Large flightless bird of Africa" .)