Right measure of current gradient (4)
I believe the answer is:
ramp
'gradient' is the definition.
(I've seen this in another clue)
'right measure of current' is the wordplay.
'right' becomes 'r' (common abbreviation).
'measure of current' becomes 'amp' (I've seen this in other clues).
'r'+'amp'='RAMP'
(Other definitions for ramp that I've seen before include "Sloping walkway" , "It gets travellers off" , "Slope for a pram" , "Sloping path between levels" , "cheat" .)