Understand and set out to process food (6)
I believe the answer is:
digest
'process food' is the definition.
(I've seen this before)
'understand and set out' is the wordplay.
'understand' becomes 'dig' (digging is a kind of understanding).
'and' means one lot of letters go next to another.
'out' indicates an anagram (out can mean wrong or inaccurate).
'set' with letters rearranged gives 'est'.
'dig'+'est'='DIGEST'
'to' acts as a link.
(Other definitions for digest that I've seen before include "Collection of shortened versions" , "Absorb and assimilate, like food" , "Periodical that summarises the news" , "result of abstraction" , "Abridgement" .)