Countries describing Europe in figures (6)
I believe the answer is:
states
'countries' is the definition.
(I know this)
'europe in figures' is the wordplay.
'europe' becomes 'E' (abbreviation eg in E number).
'in' means one lot of letters goes inside another.
'figures' becomes 'stats' (short for statistics).
'e' put within 'stats' is 'STATES'.
'describing' is the link.
(Other definitions for states that I've seen before include "America; says" , "Countries with a central government" , "Announces" , "gallery in ship" , "They're united in America" .)