Grainy food provided repeatedly, they say (6)
I believe the answer is:
cereal
'grainy food' is the definition.
(food made from grain)
'provided repeatedly they say' is the wordplay.
'provided repeatedly' becomes 'serial' (provided as part of a series).
'they say' shows a homophone (sound like).
'serial' is a homophone of 'CEREAL'.
(Other definitions for cereal that I've seen before include "Eg, wheat, rice" , "11 food, maybe" , "Starchy grains used as food" , "Grass cultivated for food" , "Relating to grain" .)