Almost never, not ever before time (6)
I believe the answer is:
nearly
'almost' is the definition.
(I know that almost can be written as nearly)
'never not ever before time' is the wordplay.
'not' suggests deleting specific letters.
'before time' becomes 'early' (I've seen this before).
'never' with 'ever' removed is 'n'.
'n'+'early'='NEARLY'
(Other definitions for nearly that I've seen before include "approximately" , "Noon at eleven fifty nine am" , "Give out a bright light" , "parsimoniously" , "Not entirely" .)