Golf disaster, filling in the holes? (5)
I believe the answer is:
grout
'filling in the holes?' is the definition.
'golf disaster' is the wordplay.
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'disaster' becomes 'rout'.
'g'+'rout'='GROUT'
(Other definitions for grout that I've seen before include "cement" , "Tile mortar" , "coarsemeal" , "Thin mortar for filling building joints etc" , "Mortar for tiling" .)