Deans turned out to be Europeans (5)
I believe the answer is:
danes
'to be europeans' is the definition.
(Danish people)
'deans turned' is the wordplay.
'turned' indicates anagramming the letters.
'deans' with letters rearranged gives 'DANES'.
'out' acts as a link.
(Other definitions for danes that I've seen before include "Vikings" , "people in Copenhagen" , "Sedan (anag.)" , "Natives of, eg, Copenhagen" , "More than one member of kingdom" .)