Not difficult at all
Option Explicit
Sub Do_Dept_Fund()
Dim ws As Worksheet
Dim sNewName As String
For Each ws In Worksheets
sNewName = Dept_Fund(ws.Range("A6").Value)
If Len(sNewName) > 0 Then ws.Name = sNewName
Next
End Sub
Private Function Dept_Fund(s As String) As String
Dim p1 As Long, p2 As Long, p3 As Long, p4 As Long
p1 = 0
p2 = 0
p3 = 0
p4 = 0
On Error GoTo NoCanDo
p1 = InStr(1, s, "(", vbBinaryCompare)
p2 = InStr(1, s, ")", vbBinaryCompare)
p3 = InStr(p1 + 1, s, "(", vbBinaryCompare)
p4 = InStr(p2 + 1, s, ")", vbBinaryCompare)
Dept_Fund = Mid(s, p3 + 1, p4 - p3 - 1) & "_" & Mid(s, p1 + 1, p2 - p1 - 1)
On Error GoTo 0
Exit Function
NoCanDo:
Dept_Fund = vbNullString
End Function