Boy conceals scheme in Finnish area (7)
I believe the answer is:
lapland
'finnish area' is the definition.
(I know that Lapland is Finnish)
'boy conceals scheme' is the wordplay.
'boy' becomes 'lad' (informal term for boy).
'conceals' indicates putting letters inside.
'scheme' becomes 'plan' (synonyms).
'lad' placed around 'plan' is 'LAPLAND'.
'in' acts as a link.
(Other definitions for lapland that I've seen before include "Arctic region" , "Region at the north of Scandinavia - Santa lives there" , "Finnish province" , "Region of northern Scandinavia and Russia" , "Father Christmas's home?" .)