South Americans in church on island (is like Pisa’s tower) (8)
I believe the answer is:
chileans
'south americans' is the definition.
(Chilean is an example)
'church on island is like pisa's tower' is the wordplay.
'church' becomes 'ch' (abbreviation on maps etc).
'on' says to put letters next to each other.
'island' becomes 'i' (geographical abbreviation).
'is like pisa's tower' becomes 'leans' (I can't explain this - if you can you should believe this answer much more).
'ch'+'i'+'leans'='CHILEANS'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for chileans that I've seen before include "countrymen" , "Natives of Santiago, say" , "people in Santiago" , "Natives of South America's longest country" .)