...Hollywood's new lot isn't altered (10)
I believe the answer is:
tinseltown
'hollywood's' is the definition.
(I've seen this before)
'new lot isn't altered' is the wordplay.
'altered' indicates an anagram.
'new'+'lot'+'isnt'='newlotisnt'
'newlotisnt' with letters rearranged gives 'TINSELTOWN'.
(Other definitions for tinseltown that I've seen before include "Name for Hollywood" , "movie industry" , "part of LA" .)