Current measures a politician outlines, finally (4)
I believe the answer is:
amps
'current measures' is the definition.
(I've seen this before)
'a politician outlines finally' is the wordplay.
'politician' becomes 'mp' (Member of Parliament).
'finally' suggests the final letters.
The last letter of 'outlines' is 's'.
'a'+'mp'+'s'='AMPS'
(Other definitions for amps that I've seen before include "concert gear" , "'Units of electric current, in short (4)'" , "Spam (anag)" , "Current measures" , "Basic units of electric current" .)