Source of minerals almost absent in this state (6)
I believe the answer is:
oregon
'this state' is the definition.
(I know that Oregon is a American state)
'source of minerals almost absent' is the wordplay.
'source of minerals' becomes 'ore' (I can't justify this - if you can you should believe this answer much more).
'almost' means to remove the last letter (most of the word but not all of it).
'absent' becomes 'gone' (similar in meaning).
'gone' with its final letter taken off is 'gon'.
'ore'+'gon'='OREGON'
'in' is the link.
Can you help me to learn more?
(Other definitions for oregon that I've seen before include "Timber" , "Old trail led here" , "Part of the US" , "State near Washington" , "Salem's state" .)