Bohemian composer came across article probing sonata vacuously (7)
I believe the answer is:
smetana
'bohemian composer' is the definition.
(I've seen this in another clue)
'came across article probing sonata vacuously' is the wordplay.
'came across' becomes 'met' (to come across is to meet or encounter).
'article' becomes 'an' (indefinite article).
'probing' indicates putting letters inside (probe can mean to poke or prod into).
'vacuously' means to remove the middle letters.
'sonata' with its centre removed is 'sa'.
'met'+'an'='metan'
'metan' placed inside 'sa' is 'SMETANA'.
(Other definitions for smetana that I've seen before include "musician" , "Bedrich ____, composer of "The Bartered Bride" and "The Kiss"" , "Czech composer, d. 1884 - Eastman (anag)" , "Nineteenth century Czech composer (The Bartered Bride)" , "maker of notes" .)