Treating tiring need? That's part of it (10)
I believe the answer is:
ingredient
'part of it' is the definition.
'ingredient' can be an answer for 'part' (thesaurus). I am unsure of the 'of it' bit.
'treating tiring need?' is the wordplay.
'treating' is an anagram indicator.
'tiring'+'need'='tiringneed'
'tiringneed' with letters rearranged gives 'INGREDIENT'.
'that's' is the link.
Can you help me to learn more?
(Other definitions for ingredient that I've seen before include "One of the things" , "Component of mixture" , "Component part" , "Something used in a recipe" , "Constituent" .)