Acne to be remedied immediately (2,4)
I believe the answer is:
at once
'immediately' is the definition.
(I've seen this before)
'acne to be remedied' is the wordplay.
'be remedied' indicates anagramming the letters.
'acne'+'to'='acneto'
'acneto' with letters rearranged gives 'AT ONCE'.
(Other definitions for at once that I've seen before include "This instant, without delay" , "without hesitation" , "Instantly" , "This minute!" , "right away" .)