Lout's acre of bottles (3)
I believe the answer is:
oaf
'lout's' is the definition.
(synonyms)
'acre of bottles' is the wordplay.
'acre' becomes 'a'.
'bottles' means one lot of letters goes inside another ('bottle' can mean to contain).
'a' put into 'of' is 'OAF'.
(Other definitions for oaf that I've seen before include "buffoon" , "Stupid or boorish man" , "Lout, lummox" , "Boorish person" , "An ill-mannered lout" .)