Rubbish I trusted foolishly (8)
I believe the answer is:
detritus
'rubbish' is the definition.
(I know that detritus is a type of rubbish)
'i trusted foolishly' is the wordplay.
'foolishly' indicates anagramming the letters.
'i'+'trusted'='itrusted'
'itrusted' with letters rearranged gives 'DETRITUS'.
(Other definitions for detritus that I've seen before include "Any kind of debris" , "Remains" , "Debris, rubble" , "Accumulated debris" , "Worn down rocks, gravel etc." .)