Tied off range of food (4)
I believe the answer is:
diet
'range of food' is the definition.
'diet' can be an answer for 'food' (diet is a kind of food). I am not certain of the 'range of' bit.
'tied off' is the wordplay.
'off' indicates anagramming the letters.
'tied' with letters rearranged gives 'DIET'.
Can you help me to learn more?
(Other definitions for diet that I've seen before include "Assembly; eat less food" , "Fast - food - convention" , "go without sugar perhaps" , "Restriction of food intake" , "Restricted cheer" .)