Worried about foreign currency in the borders of Thailand (8)
I believe the answer is:
troubled
'worried' is the definition.
('troubled' can be a synonym of 'worried')
'foreign currency in the borders of thailand' is the wordplay.
'foreign currency' becomes 'rouble' (I've seen this in other clues).
'in the' is an insertion indicator.
'borders of' says to hollow out the word (remove centre letters).
'thailand' with its centre taken out is 'td'.
'rouble' inserted within 'td' is 'TROUBLED'.
'about' acts as a link.
(Other definitions for troubled that I've seen before include "Anxious" , "Disturbed, bothered" , "Bothered, disquieted" , "Inconvenienced" , "Worried" .)