A country once losing money — or a number of countries (4)
I believe the answer is:
asia
'a number of countries' is the definition.
(Asia is a continent)
'a country once losing money' is the wordplay.
'country once' becomes 'siam' (former name of Thailand).
'losing' is a deletion indicator.
'money' becomes 'm' (abbreviation in economics).
'siam' with 'm' taken out is 'sia'.
'a'+'sia'='ASIA'
'or' is the link.
(Other definitions for asia that I've seen before include "Huge landmass" , "Populous continent" , "Part of the world" , "huge region" , "One-third of all land" .)