One very old language covers nothing by itself, in this (9)
I believe the answer is:
isolation
'by itself in this' is the definition.
(isolated people are on their own)
'one very old language covers nothing' is the wordplay.
'one' becomes 'i' (Roman numeral).
'very' becomes 'so' (I've seen this in other clues).
'old language' becomes 'latin' (I've seen this before).
'covers' indicates putting letters inside.
'nothing' becomes 'o' (looks like zero - 0).
'latin' placed around 'o' is 'lation'.
'i'+'so'+'lation'='ISOLATION'
(Other definitions for isolation that I've seen before include "Remoteness" , "Quarantine; solitude" , "Cutting off" , "Being separated" , "Separation - solitude" .)