Duke only turning up in Greek island (5)
I believe the answer is:
delos
'greek island' is the definition.
(I've seen this before)
'duke only turning up' is the wordplay.
'duke' becomes 'd' (abbreviation).
'only' becomes 'sole' (synonyms).
'turning up' says the letters should be written backwards.
'sole' in reverse letter order is 'elos'.
'd'+'elos'='DELOS'
'in' is the link.
(Other definitions for delos that I've seen before include "Greek island, supposed birthplace of Apollo" , "Island of the Cyclades" , "Apollo's birthplace" .)