Relative returns from Greece incognito (5)
I believe the answer is:
niece
'relative' is the definition.
(type of relative)
'returns from greece incognito' is the wordplay.
'returns' says the letters should be written in reverse.
'from' indicates the answer is hidden within the clue.
'ecein' is hidden within 'greece incognito'.
'ecein' reversed gives 'NIECE'.
(Other definitions for niece that I've seen before include "Female relation" , "One of the family" , "Female family member" , "Brother's girl" , "Criminal" .)