Figures showing one ton in quarters (6)
I believe the answer is:
digits
'figures' is the definition.
(I know this)
'one ton in quarters' is the wordplay.
'one' becomes 'I' (Roman numeral).
'ton' becomes 't' (abbreviation).
'in' means one lot of letters goes inside another.
'quarters' becomes 'digs' (digs is a kind of quarters).
'i'+'t'='it'
'it' put inside 'digs' is 'DIGITS'.
'showing' acts as a link.
(Other definitions for digits that I've seen before include "Fingers, toes and numbers" , "Numbers 0 to 9" , "One to nine" .)