American grog mixture brings trouble (5)
I believe the answer is:
aggro
'trouble' is the definition.
(short for aggression or aggravation)
'american grog mixture' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'mixture' indicates an anagram.
'grog' anagrammed gives 'ggro'.
'a'+'ggro'='AGGRO'
'brings' is the link.
(Other definitions for aggro that I've seen before include "Violence - difficulties" , "Aggressive, violent behaviour in short" , "Antisocial behaviour" , "Hostile troublemaking" , "Fighting" .)