Twice the amount (6)
I believe the answer is:
double
'twice the amount' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for double that I've seen before include "Orwellian acceptance of conflicting principles" , "Multiply by two" , "Bed for two people" , "Score of forty with one dart, perhaps?" , "Twice, the size say" .)