Candidate in the end failing to pass (6)
I believe the answer is:
elapse
'pass' is the definition.
(I know that pass can be written as elapse)
'candidate in the end failing' is the wordplay.
'in the end' suggests the final letters.
'failing' becomes 'lapse' (a moral failing).
The final letter of 'candidate' is 'e'.
'e'+'lapse'='ELAPSE'
'to' acts as a link.
(Other definitions for elapse that I've seen before include "run by" , "Go past" , "Glide by" , "Tick by" , "Go by - pass away" .)