Carefully determine what's cooked in feed (6)
I believe the answer is:
define
'carefully determine' is the definition.
'define' can be an answer for 'determine' (defining is a kind of determining). I am not sure about the 'carefully' bit.
'cooked in feed' is the wordplay.
'cooked' indicates anagramming the letters.
'in'+'feed'='infeed'
'infeed' is an anagram of 'DEFINE'.
'what's' acts as a link.
Can you help me to learn more?
(Other definitions for define that I've seen before include "Give exact meaning as of a word" , "Give precise meaning" , "Fix the meaning of" , "Describe exactly" , "Explain the meaning of a word" .)