Checks acne being upset (5)
I believe the answer is:
stops
'checks' is the definition.
(I know this)
'acne being upset' is the wordplay.
'acne' becomes 'spots' (I've seen this before).
'being upset' says the letters should be written backwards.
'spots' back-to-front is 'STOPS'.
(Other definitions for stops that I've seen before include "Ceases" , "Prevents" , "Discontinues" , "Checks" , "Ends" .)