Crossword Genius

One on course has this useful sounding headgear (8)

Ross

I believe the answer is:

handicap

'one on course has this' is the definition.
(golf course)

'useful sounding headgear' is the wordplay.
'useful' becomes 'handy' (I've seen this before).
'sounding' shows a homophone (sound like).
'headgear' becomes 'cap' (cap is a kind of headgear).
'handy' sounds like 'handi'.
'handi'+'cap'='HANDICAP'

(Other definitions for handicap that I've seen before include "It impedes or hinders" , "Impede" , "race" , "Disadvantage to offset an advantage to equalise chances of winning" , "Grand National for example" .)

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