Drunk on pungent gin stirred at the top (4,7)

'at the top' is the definition.
(ranking high in an organisation)

'drunk on pungent gin stirred' is the wordplay.
'drunk' becomes 'high' (I've seen this before).
'on' is an insertion indicator (as in clothing 'on' a person).
'pungent' becomes 'rank' (both can mean horribly smelly).
'stirred' indicates anagramming the letters.
'gin' anagrammed gives 'ing'.
'rank' put within 'ing' is 'ranking'.
'high'+'ranking'='HIGH-RANKING'