Benefit from old saying about never, at the outset, cutting tax (9)
I believe the answer is:
advantage
'benefit' is the definition.
(thesaurus)
'old saying about never at the outset cutting tax' is the wordplay.
'old saying' becomes 'adage' (I've seen this before).
'about' means one lot of letters goes inside another.
'at the outset' says to take the initial letters.
'cutting' means one lot of letters goes inside another (some letters cut their way into a word).
'tax' becomes 'vat' (British sales tax).
The initial letter of 'never' is 'n'.
'n' going inside 'vat' is 'vant'.
'adage' enclosing 'vant' is 'ADVANTAGE'.
'from' acts as a link.
(Other definitions for advantage that I've seen before include "First point scored after deuce in tennis" , "Favourable circumstance" , "Benefit - superior position" , "Privilege" , "Asset" .)