trim

How about this?

For Each rCell In Selection

rCell.Value = Trim(rCell.Value)

Next

You should dimension the rCell variable at the top of your code

Dim rCell as range

It's not clear how the range is populated - presumably constants ?

If so you could get away with a single Evaluate call, ie:

Sub Example()
With Range("A140",Range("A140").End(xlDown).End(xlToRight))
    .Value = Evaluate("IF(ISTEXT(" & .Address & "),TRIM(" & .Address & "),REPT(" & .Address & ",1))")
End With
End Sub

It's not clear what appears after this range of interest - if anything - you might want to revisit the selection process as you could end up processing a very big range (unintentionally)