Some Cypriot assumed to be Greek character (4)
I believe the answer is:
iota
'greek character' is the definition.
(letter from the Greek alphabet)
'some cypriot assumed to' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'IOTA' is hidden within 'cypriot assumed to'.
'be' acts as a link.
(Other definitions for iota that I've seen before include "Tiny piece" , "Ninth Greek character" , "Tiny or scarcely detectable amount" , "Contrivance" , "Foreign character" .)