A new job all but secure (6)
I believe the answer is:
anchor
'secure' is the definition.
(I know that anchor is a type of secure)
'a new job all but' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'job' becomes 'chore' (synonyms).
'all but' means to remove the last letter ('all but' can mean 'almost' or 'nearly').
'chore' with its last letter taken off is 'chor'.
'a'+'n'+'chor'='ANCHOR'
(Other definitions for anchor that I've seen before include "A weight to secure in place" , "Secure (something) firmly in position" , "Member of relay team" , "Mainstay" , "Weigh down" .)