Holes give Georgia an afterthought (4)
I believe the answer is:
gaps
'holes' is the definition.
(I've seen this in another clue)
'give georgia an afterthought' is the wordplay.
'give' means one lot of letters go next to another.
'georgia' becomes 'GA' (abbreviation for the US state).
'an afterthought' becomes 'ps' (ps stands for postscript).
'ga' put next to 'ps' is 'GAPS'.
(Other definitions for gaps that I've seen before include "Breaks, spaces" , "Breaks or openings as in hedge or fence" .)