[R] Replacing elements of a list over a certain threshold

[Jim Hargreaves]

Dear List,

I have a list of length ~1000 filled with numerics. I need to replace 
the elements of this list that are above a certain numerical threshold 
with the value of the threshold.

e.g
example=list(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1)
threshold=5
<magic code goes here>
example=(1, 2, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 3, 2, 1).

I have written a crude script that achieves this but it's very slow. Is 
there a way to do this using some R function?

Crude script: http://pastebin.com/3KSfi8nD