Relative in Greece inebriated, doing a somersault (5)
I believe the answer is:
niece
'relative' is the definition.
(type of relative)
'in greece inebriated doing a somersault' is the wordplay.
'in' indicates a hidden word.
'a somersault' is a reversal indicator.
'ecein' can be found hidden inside 'greece inebriated doing'.
'ecein' in reverse letter order is 'NIECE'.
(Other definitions for niece that I've seen before include "girl further down the line" , "Brother's daughter" , "member of different generation" , "Criminal" , "Brother or sister's daughter" .)