The capital has foreign currency difficulties (8)
I believe the answer is:
troubles
'difficulties' is the definition.
(I know this)
'the capital has foreign currency' is the wordplay.
'capital' indicates taking the first letters.
'has' is a charade indicator (letters next to each other).
'foreign currency' becomes 'roubles'.
The initial letter of 'the' is 't'.
't'+'roubles'='TROUBLES'
(Other definitions for troubles that I've seen before include "Problems and difficulties - subtle or what?" , "Pack them up in your old kit bag and smile" , "Distressing or painful events" , "Difficulties, worries" , "Inconveniences, perturbs" .)