Mix our two tins to provide nourishment (9)
I believe the answer is:
nutrition
'nourishment' is the definition.
(I know that nourishment can be written as nutrition)
'mix our two tins' is the wordplay.
'two tins' can mean two replacements for 'tin'.
'mix' indicates anagramming the letters.
'our'+'tin'+'tin'='ourtintin'
'ourtintin' is an anagram of 'NUTRITION'.
'to provide' acts as a link.
(Other definitions for nutrition that I've seen before include "Act of nourishing" , "Food, its study" , "Food, nourishment" , "what's taken in?" , "form of sustenance" .)