Sexton in Cairns sat out (9)
I believe the answer is:
sacristan
'sexton' is the definition.
(synonyms)
'cairns sat out' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'cairns'+'sat'='cairnssat'
'cairnssat' with letters rearranged gives 'SACRISTAN'.
'in' acts as a link.
(Other definitions for sacristan that I've seen before include "Sexton" , "Church officer in charge of sacred vessels etc" , "Church official" , "Church officer in charge of sacred objects" , "Church worker" .)