Some current map adjusted before (6)
I believe the answer is:
ampere
'some current' is the definition.
'map adjusted before' is the wordplay.
'adjusted' indicates an anagram.
'before' becomes 'ere' (usually literary).
'map' is an anagram of 'amp'.
'amp'+'ere'='AMPERE'
(Other definitions for ampere that I've seen before include "Solenoid inventor" , "Current measure" , "scientist" , "Unit measured by 17 across" , "Unit of currency" .)