Foolishly tied to what one eats (4)
I believe the answer is:
diet
'what one eats' is the definition.
(I've seen this before)
'foolishly tied' is the wordplay.
'foolishly' indicates anagramming the letters.
'tied' with letters rearranged gives 'DIET'.
'to' is the link.
(Other definitions for diet that I've seen before include "Calorie-watching regimen" , "Regimen for eating" , "Assembly; eat less food" , "Restricted cheer" , "Food - parliament" .)