Strong wind on northern area reveals mineral deposit (6)
I believe the answer is:
galena
'mineral deposit' is the definition.
(galena is an ore of lead)
'strong wind on northern area' is the wordplay.
'strong wind' becomes 'gale' (I've seen this before).
'on' is a charade indicator (letters next to each other).
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'area' becomes 'a' (maths abbreviation).
'gale'+'n'+'a'='GALENA'
'reveals' is the link.
(Other definitions for galena that I've seen before include "Angela (anag) - ore producing lead" , "Lead sulphide mineral" , "Len, GAA produces lead sulphide" , "Commonest ore of lead - Angle "A" (anag)" .)