Lead ore (6)
I believe the answer is:
galena
'lead ore' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for galena that I've seen before include "Len, GAA produces lead sulphide" , "Commonest ore of lead - Angle "A" (anag)" , "Angela (anag) - ore producing lead" , "Lead sulphide mineral" .)