Country producing oil we hear (6)
I believe the answer is:
Here is my best explanation:
'country' is the definition.
(Greece is an example)
'oil we hear' is the subsidiary indication.
'oil' becomes 'grease' (grease is a kind of oil).
'we hear' indicates a 'sounds like' (homophone) clue.
'grease' is a homophone of 'greece'.
'producing' is the link.
(Other definitions for greece that I've seen before include "European state", ""The cradle of civilisation"", "Mediterranean republic", "Mediterranean country", "Country of southeast Europe", "Athens its capital", "Southern European country", "Country of Sophocles and Aristotle", "Hellenic Republic" and "Hellenic republic".)