Support a mineral cure (7)
I believe the answer is:
restore
'cure' is the definition.
(I've seen this before)
'support a mineral' is the wordplay.
'support' becomes 'rest' (e.g. a shoulder rest is a support for shoulder).
'a mineral' becomes 'ore' (ore is a kind of mineral).
'rest'+'ore'='RESTORE'
(Other definitions for restore that I've seen before include "Strengthen" , "Bring back; repair" , "Repair, renovate" , "Repair, put back" , "Return to original condition" .)