Take in repast regularly? (3)
I believe the answer is:
'take in' is the definition.
(to eat is to take in food)
'repast regularly?' is the wordplay.
'regularly?' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternating letters of 'repast' are 'EAT'.
(Other definitions for eat that I've seen before include "Devour" , "Take food" , "Dine in a restaurant" , "Corrode" , "and 27: Be humiliated" .)