Mineral source almost disappeared from Pacific state (3)
I believe the answer is:
ore
'mineral source' is the definition.
(I've seen this before)
'almost disappeared from pacific state' is the wordplay.
I cannot quite see how this works, but
'from' could be 'e' (I've seen this in other clues) and 'e' is found within the answer.
'state' could be 'or' and 'or' is present in the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
(Other definitions for ore that I've seen before include "Natural material from which metals can be extracted" , "Mineral - Scandinavian money" , "Raw iron" , "coinage" , "Natural minerals" .)