I have never heard "nominalised clause." Generally we nominalize verbs and adjectives: clause: clean the house Nominalising the verb: Cleaning the house... "Cleaning the house" now functions as a noun and is used as such.

This is when a verb or word other than a noun becomes a noun in the context of the sentence.: The reconstruction of the building moved forward. (what moved forward? An object? No. An verb acting as a noun.) The phrase in this example is 'reconstruction of the building.'