Punctual reminder (6)
I believe the answer is:
prompt
I believe this is a double definition.
'punctual' is the first definition.
('prompt' can be similar in meaning to 'punctual')
'reminder' is the second definition.
(thesaurus)
(Other definitions for prompt that I've seen before include "Cue given to actor" , "Give hint as to actor who has forgotten lines (6)" , "Cue given to a performer" , "Bring about; on time" , "Spurs do this" .)