Cooking meals in -- that's basic! (7)
I believe the answer is:
seminal
'basic' is the definition.
(thesaurus)
'cooking meals in' is the wordplay.
'cooking' is an anagram indicator.
'meals'+'in'='mealsin'
'mealsin' with letters rearranged gives 'SEMINAL'.
'that's' acts as a link.
(Other definitions for seminal that I've seen before include "Having strong later influence" , "Strongly influencing future developments" , "Original and influential" , "Highly original" , "Generating new developments for menials" .)