Plotting works because Plot has the Attribute HoldAll. The function cle will stay unevaluated until the plot-routines feed it with numeric values.
So you have to delay execution of cle until concrete values will be given to it.
An usual way to achieve this is to declare:
Your notebook has been incomplete; I created a silly example (the Graphics have been deleted before posting to keep the attachment small).
Attachment: anotherFindfit.nb, URL: ,