Indication to mix gins (4)
I believe the answer is:
sign
'indication' is the definition.
(I've seen this before)
'mix gins' is the wordplay.
'mix' is an anagram indicator.
'gins' with letters rearranged gives 'SIGN'.
'to' acts as a link.
(Other definitions for sign that I've seen before include "Engage by written agreement" , "house" , "Endorse" , "Communicate silently" , "As the star was for 14 across" .)