They tell people when to be dutiful (5)
I believe the answer is:
rotas
'they tell people' is the definition.
The definition suggests an adverb but the answer is not.
'when to be dutiful' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'be dutiful' becomes 'rot' (I can't explain this - if you can you should believe this answer much more).
'as' after 'rot' is 'ROTAS'.
Can you help me to learn more?
(Other definitions for rotas that I've seen before include "they tell us when to work" , "Duty lists" , "Rolls" , "Cycles of duty" , "Rosters" .)