Signal to mix gins (4)
I believe the answer is:
sign
'signal' is the definition.
(I know that signal can be written as sign)
'mix gins' is the wordplay.
'mix' indicates anagramming the letters.
'gins' is an anagram of 'SIGN'.
'to' acts as a link.
(Other definitions for sign that I've seen before include "Put one's name to a document" , "Notice; omen" , "Augury" , "Manifestation" , "Indicator" .)