Flipping crazy golfer's after new holes (7)
I believe the answer is:
tunnels
'holes' is the definition.
(tunnel is a kind of hole)
'flipping crazy golfer's after new' is the wordplay.
'flipping' shows that the letters should be reversed in order.
'crazy' becomes 'nut' (I've seen this before**).
'golfer' becomes 'els' (Ernie Els - former number one professional golfer).
'after' means one lot of letters go next to another.
'new' becomes 'n'.
'nut' reversed gives 'tun'.
'els' after 'n' is 'nels'.
'tun'+'nels'='TUNNELS'
(Another definition for tunnels that I've seen is " Underground passages".)