Sorting out musical instrument, I blow the whistle (10)

I believe the answer is:

organising

'sorting out' is the definition.

'musical instrument i blow the whistle' is the wordplay.
'musical instrument' becomes 'organ' (organ is a kind of musical instrument).
'blow the whistle' becomes 'sing' (I've seen this before).
'organ'+'i'+'sing'='ORGANISING'

(Other definitions for organising that I've seen before include "arrangement" , "Systematically arranging" .)

I've seen this clue in The Telegraph.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.