Input: part 1 + W(left_1_right) + part 3
Required output: part 1 + W(1) + part 3
Sub Macro1()
Range("A1").Value = "part 1 + W(left_1_right) + part 3"
Range("A1").Replace What:="W(*1*)", Replacement:="W(1)", LookAt:=xlPart
End Sub