Pass with bad grade before failure (6)
I believe the answer is:
elapse
'pass' is the definition.
(I know that pass can be written as elapse)
'bad grade before failure' is the wordplay.
'bad grade' becomes 'e' (bad academic grade).
'before' says to put letters next to each other.
'failure' becomes 'lapse' (lapse is a kind of failure).
'e'+'lapse'='ELAPSE'
'with' acts as a link.
(Other definitions for elapse that I've seen before include "Glide by" , "(Of time) go by" , "Please (anag) -- pass away" , "Slip away" , "Go past" .)