A politician concerned in current affairs (3)
I believe the answer is:
amp
'a' is the definition.
(A is the symbol for the amp or ampere)
'politician concerned in current affairs' is the wordplay.
I cannot really see how this works, but
'politician' could be 'mp' (Member of Parliament) and 'mp' is found in the answer.
A single letter 'a' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for amp that I've seen before include "Current measure" , "Current; hi-fi kit" , "Unit of electricity, in short" , "measure of power" , "Unit of electric current - short version" .)