Intake ultimately failing to pass (6)
I believe the answer is:
elapse
'pass' is the definition.
(synonyms)
'intake ultimately failing' is the wordplay.
'ultimately' suggests the final letters.
'failing' becomes 'lapse' (a moral failing).
The last letter of 'intake' is 'e'.
'e'+'lapse'='ELAPSE'
'to' is the link.
(Other definitions for elapse that I've seen before include "Please (anag) -- pass away" , "Tick by" , "Go past" , "pass in silence" , "Of time, pass by - please" .)