First of all ask maestro about the Italian violin (5)
I believe the answer is:
amati
'violin' is the definition.
(I've seen this before)
'first of all ask maestro about the italian' is the wordplay.
'first of all' indicates taking the first letters.
'italian' becomes 'i'.
The first letters of 'ask maestro about the' is 'amat'.
'amat'+'i'='AMATI'
(Other definitions for amati that I've seen before include "Italian family of violin-makers" , "fiddler" , "Craftsman" , "family of craftsmen" , "instrument-maker" .)