Corresponded with everything in new diet (7)
I believe the answer is:
tallied
'corresponded' is the definition.
('tally' can be a synonym of 'correspond')
'everything in new diet' is the wordplay.
'everything' becomes 'all' (all things).
'in' is an insertion indicator.
'new' indicates anagramming the letters.
'diet' anagrammed gives 'tied'.
'all' inserted inside 'tied' is 'TALLIED'.
'with' acts as a link.
(Other definitions for tallied that I've seen before include "Agreed; calculated" , "Agreed, corresponded" , "Corresponded - kept score" , "Matched" , "Reckoned debt or score" .)