The final section of the histogram changed (4,8)
I believe the answer is:
home straight
'the final section' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'the histogram changed' is the wordplay.
'changed' indicates an anagram.
'the'+'histogram'='thehistogram'
'thehistogram' is an anagram of 'HOME STRAIGHT'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for home straight that I've seen before include "Final stage of a racecourse" , "covered in neat report" , "Last stage of race" , "Last part of a race" , "final stage of race" .)