Compatriots reckon right, millions invested in foreign currency (10)
I believe the answer is:
countrymen
'compatriots' is the definition.
('countryman' can be a synonym of 'compatriot')
'reckon right millions invested in foreign currency' is the wordplay.
'reckon' becomes 'count' (I've seen this before**).
'right' becomes 'r' (common abbreviation).
'millions' becomes 'm' (abbreviation).
'invested in' is an insertion indicator.
'foreign currency' becomes 'yen' (I've seen this before).
'm' inserted inside 'yen' is 'ymen'.
'count'+'r'+'ymen'='COUNTRYMEN'
(Other definitions for countrymen that I've seen before include "Rustic types" , "Ruralists" , "rustics" , "going after Romans in play" , "closely following Romans?" .)