For Greg Norman's son, golf is the open sesame (8)
I believe the answer is:
passport
'is the open sesame' is the definition.
(I've seen this before)
'for greg norman's son golf' is the wordplay.
I cannot really see how this works, but
'son' could be 'ss' (I've seen this in other clues) and 'ss' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for passport that I've seen before include "Traveller's aid" , "Official document required for international travel" , "Travel ID" , "entry permit?" , "Document to allow entry to another country" .)