Highest standard number (9)
I believe the answer is:
paramount
'highest' is the definition.
(I've seen this before)
'standard number' is the wordplay.
'standard' becomes 'par' (standard of play in golf).
'number' becomes 'amount' (I've seen this in another clue).
'par'+'amount'='PARAMOUNT'
(Other definitions for paramount that I've seen before include "Pre-eminent - movie maker" , "Of the greatest importance" , "First" , "Predominant" , "Of overriding importance" .)