Right click on the sheet tab and select view code
put in code like this
Private Sub Worksheet_SelectionChange(ByVal Target As Excel.Range)
if Target.count > 1 then exit sub
if Target.column = 3 then
nameofyourmacro
End if
End Sub
3 is column C. Change to identify your column.
If your macro will change the selection, you might want to disable events
Private Sub Worksheet_SelectionChange(ByVal Target As Excel.Range)
if Target.count > 1 then exit sub
On Error goto ErrHandler
if Target.column = 3 then
Application.EnableEvents = False
nameofyourmacro
End if
ErrHandler:
Application.EnableEvents = True
End Sub