He stops at break promptly! (9)

I believe the answer is:

posthaste

'promptly' is the definition.
(thesaurus)

'he stops at break' is the wordplay.
'break' indicates an anagram.
'he'+'stops'+'at'='hestopsat'
'hestopsat' anagrammed gives 'POSTHASTE'.

(Other definitions for posthaste that I've seen before include "Like Bat out of Hell" , "Speedily" , "immediately" , "With particular speed" , "at the double" .)

I've seen this clue in The Telegraph.

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