Organ stop (5)

I believe the answer is:

colon

This clue is a double definition.

'organ' is the first definition.
(colon is a kind of organ)

'stop' is the second definition.
(thesaurus)

(Other definitions for colon that I've seen before include ": - bit of the gut" , "cash" , "Punctuation mark; gut" , "Stop (on the inside!)" , "Start of one canal" .)

I've seen this clue in The Telegraph.

Want a hint initially instead of a full solution? Install my app