Figures under a pound in extensive range (9)
I believe the answer is:
apennines
'extensive range' is the definition.
(mountain range)
'figures under a pound' is the wordplay.
'figures' becomes 'nines'.
'under' says to put letters next to each other.
'pound' becomes 'pen' (I've seen this before).
'a'+'pen'='apen'
'nines' after 'apen' is 'APENNINES'.
'in' is the link.
(Other definitions for apennines that I've seen before include "Italian mountain range" , "Mountain range in central Italy" , "Great mountain range in Italy (9)" , "Italian mountain chain" , "Italian mountains" .)