How someone on Mount Rushmore looks over the top (6,4,4)
I believe the answer is:
larger than life
I believe this clue is a double definition.
'how someone on mount rushmore looks' is the first definition.
(the figures on Mount Rushmore are not to scale)
'over the top' is the second definition.
(larger than life can mean over the top)
(Other definitions for larger than life that I've seen before include "very imposing" , "Extravagant" , "circulation claim by another old American magazine?" , "Exaggerated" .)