Grow significantly more when taking mineral (4)
I believe the answer is:
farm
'grow' is the definition.
(I know that grow can be written as farm)
'significantly more when taking mineral' is the wordplay.
'significantly' becomes 'far' (I've seen this in another clue).
'when taking' suggests deleting specific letters.
'mineral' becomes 'ore' (ore is a kind of mineral).
'more' with 'ore' removed is 'm'.
'far'+'m'='FARM'
(Other definitions for farm that I've seen before include "agricultural centre" , "Cold Comfort --" , "See 5" , "Homestead" , "and 27: Source of meat" .)