Style of architecture in Finland, or Iceland (5)
I believe the answer is:
doric
'style of architecture' is the definition.
(Doric order is a classical architectural order)
'in finland or iceland' is the wordplay.
'in' says the answer is hidden in the clue.
'DORIC' is hidden in the letters of 'finland or iceland'.
(Other definitions for doric that I've seen before include "One of the Greek orders of architecture" , "One classical order in architecture" , "Plainest order of Gk. architecture" , "A classical style of architecture with fluted columns" , "Greek architectural style" .)