Inform how to mix gins (4)
I believe the answer is:
sing
'inform' is the definition.
(I know that sing is a more specific form of the action break)
'to mix gins' is the wordplay.
'to mix' is an anagram indicator.
'gins' anagrammed gives 'SING'.
'how' acts as a link.
(Other definitions for sing that I've seen before include "Act as informer" , "Inform - carol" , "Chorus" , "behave like noisy tits" , "Grass" .)