Sure, very easy really. This code must be placed in the Private Module of the Sheet Object. To do this. right click on the sheet name tab nad select "View Code".
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address = "$A$1" Then
If IsNumeric(Target) Then
Target = Choose(Target, "Dental", "Doctor", "Vet", "Surgeon")
End If
End If
End Sub
This one is geared for numeric entries only in cell A1. If you type 1, then Enter you get "Dental" if 2 "Doctor" etc.
If however you want text as well use the Select case.
Option Explicit
Option Compare Text
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address = "$A$1" Then
Select Case Target.Value
Case 1
Target = "Dental"
Case 2 To 5
Target = "Doctor"
Case Is > 10
Target = "Fred"
Case "Octopus"
Target = "Squid"
End Select
End If
End Sub
Remove the "Option Compare Text" Statement for case sensitivity.