Try this macro:
Private Sub Worksheet_Change(ByVal Target As Range)
On Error GoTo ErrHandler
If Not Intersect(Target, Me.Range("A1:A10")) Is Nothing Then
Application.EnableEvents = False
Target.Offset(0, 2).ClearContents
End If
ErrHandler:
Application.EnableEvents = True
End Sub
This assumes you have drop downs in the range A1:10. Change range to suit.
To use this, select the sheet where you want this to happen.
Right click on the sheet tab
Select View Code
Paste the above code into the window that opens
Hit ALT Q or close the window by clicking the X to return to Excel.

Signature
Biff
Microsoft Excel MVP
>I have cells on the worksheet that when you select an option from a drop
>down
[quoted text clipped - 8 lines]
> Thanks in advance
> MP