Trust one to feed new cleaner (8)
I believe the answer is:
reliance
'trust' is the definition.
(reliance is a kind of trust)
'one to feed new cleaner' is the wordplay.
'one' becomes 'i' (Roman numeral).
'to feed' indicates putting letters inside.
'new' is an anagram indicator.
'cleaner' anagrammed gives 'relance'.
'i' inserted within 'relance' is 'RELIANCE'.
(Other definitions for reliance that I've seen before include "Trust or confidence" , "Faith" , "Dependence (on something)" , "Dependence, trust" , "Trust - in cereal (anag)" .)