It's natural in food we hear (6)
I believe the answer is:
inbred
'it's natural' is the definition.
('inbred' can be similar in meaning to 'natural')
'in food we hear' is the wordplay.
'food' becomes 'bread' (bread is a kind of food).
'we hear' indicates a 'sounds like' (homophone) clue.
'bread' sounds like 'bred'.
'in'+'bred'='INBRED'
(Other definitions for inbred that I've seen before include "Congenital - unwisely inter-related" , "Lacking genetic variety" , "Present by nature" , "From too-closely-related family" , "Was deep in thought" .)