Mountain originally broken in seven pieces (3,5)
I believe the answer is:
ben nevis
'mountain' is the definition.
(mountain in Scotland)
'originally broken in seven pieces' is the wordplay.
'originally' suggests taking the first letters.
'pieces' is an anagram indicator (the same pieces in a new order).
The first letter of 'broken' is 'b'.
'in'+'seven'='inseven'
'inseven' is an anagram of 'ennevis'.
'b'+'ennevis'='BEN NEVIS'
(Other definitions for ben nevis that I've seen before include "Britain's highest mountain" , "The highest peak in Scotland" , "top position up North" , "Highest peak in Great Britain" , "Highest UK mountain" .)