I would suggest using a double click instead of a single click to insert the check mark. This would prevent you from accidentally inserting a check mark if you mistakenly click the cell. If you want to use a single click, then do the following: right click the tab name for your sheet and click 'View Code'. Paste the first macro below into the empty code window that opens up. Close the code window to return to your sheet. If you want to use a double click, use the second macro instead. Please note that the code is written to use cell A1 as the target cell. Change the target cell (in red) to suit your needs.
Rich (BB code):
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.CountLarge > 1 Then Exit Sub
If Intersect(Target, Range("A1")) Is Nothing Then Exit Sub
If Target = "" Then
Target.Value = ChrW(&H2713)
Else
Target.ClearContents
End If
End Sub
Rich (BB code):
Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, Cancel As Boolean)
If Target.CountLarge > 1 Then Exit Sub
If Intersect(Target, Range("A1")) Is Nothing Then Exit Sub
If Target = "" Then
Target.Value = ChrW(&H2713)
Else
Target.ClearContents
End If
End Sub