1: Incomprehensible English is the sign of a professional (7)
4: Song describing rat in a place of calm and beauty (7)
7: Current interruption has Republican upset (7)
9: Aria Sue belted for a very big hunk?(7)
11: Perfect counter-spy equipment (3)
13: Migrate to swing and Joplin tunes (7)
14: Rode with colleagues and complained about John's return (9)
15: Is next to a total bust (5)
17: Shatters ice cubes (5)
18: Bride's outfit - a sort of shirt by Jean-Jacques? (9)
20: Left behind? Shiver violently and wither (7)
22: 4-down Arias hit high note in some of the lungs (3,3)
23: Therefore, finish off this bit of work (3)
24: In retrospect, no howls of laughter sounded deliberate (5,2)
25: Four qts consumed by a statue that came to life (7)
26: Nuisance was enticed to be thoroughly ground down.(7)
27: Grovelling to small liberal (7)