Greek character goes around northern volcano (4)
I believe the answer is:
etna
'volcano' is the definition.
(Etna is an example)
'greek character goes around northern' is the wordplay.
'greek character' becomes 'eta' (letter from the Greek alphabet**).
'goes around' means one lot of letters goes inside another.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'eta' going around 'n' is 'ETNA'.
(Other definitions for etna that I've seen before include "A feature of Sicily" , "one blowing top?" , "Neat volcano overturned" , "Volcano in Sicily, quite neat" , "Dangerous peak" .)