Food in repast is oddly deficient (4)
I believe the answer is:
eats
'food' is the definition.
(eats can mean food)
'repast is oddly deficient' is the wordplay.
'oddly deficient' means one should take alternating letters (letters in odd-numbered positions removed).
'repast'+'is'='repastis'
The alternate letters of 'repastis' are 'EATS'.
'in' is the link.
(Other definitions for eats that I've seen before include "Devours - food" , "Sate (anag.)" , "Grazes perhaps" , "Tuck" , "Food (slang)" .)