Fifty in Connecticut with American medicine (7)
I believe the answer is:
linctus
'medicine' is the definition.
(thesaurus)
'fifty in connecticut with american' is the wordplay.
'fifty' becomes 'l' (roman numeral).
'connecticut' becomes 'ct'.
'with' says to put letters next to each other.
'american' becomes 'us'.
'l'+'in'+'ct'+'us'='LINCTUS'
(Other definitions for linctus that I've seen before include "Cough-medicine" , "Soothing drink" , "Cough medicine" , "Syrupy medicine to relieve sore throats" , "Thick liquid medicine" .)