Always without, failing to get by (9)
I believe the answer is:
eternally
'always' is the definition.
(I've seen this in another clue)
'without failing to get by' is the wordplay.
'without' becomes 'externally' ('without' can mean on the outside).
'failing to get' indicates named letters should be taken away.
'by' becomes 'x' (multiplication sign).
'externally' with 'x' removed is 'ETERNALLY'.
(Other definitions for eternally that I've seen before include "Always and ever" , "constantly" , "For evermore" , "all the time" , "Nearly let out forever" .)