Pope upset the backwards Spanish race (6)
I believe the answer is:
people
'race' is the definition.
(I know that race can be written as people)
'pope upset the backwards spanish' is the wordplay.
'upset' is an anagram indicator.
'the backwards' says the letters should be written in reverse.
'spanish' becomes 'el' (I've seen this in other clues).
'el' back-to-front is 'le'.
'pope' with letters rearranged gives 'peop'.
'peop'+'le'='PEOPLE'
(Other definitions for people that I've seen before include "Human beings in general" , "Population" , "Race - mankind" , "country folk" , "Nation" .)