Scotsman at home with one Italian composer (7)
I believe the answer is:
rossini
'italian composer' is the definition.
(I've seen this before)
'scotsman at home with one' is the wordplay.
'scotsman' becomes 'ross' (common Scottish name).
'at home' becomes 'in' ('in' can be similar in meaning to 'at home').
'with' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
'ross'+'in'+'i'='ROSSINI'
(Other definitions for rossini that I've seen before include "He composed operas" , "Barber of Seville writer" , "he produced harmony" , "Staff writer" , "Italian composer, 1792-1868" .)