Trojan leader has currency difficulty (7)
I believe the answer is:
trouble
'difficulty' is the definition.
(synonyms)
'trojan leader has currency' is the wordplay.
'leader' says to take the initial letters.
'has' says to put letters next to each other.
'currency' becomes 'rouble' (Russian rouble).
The initial letter of 'trojan' is 't'.
't'+'rouble'='TROUBLE'
(Other definitions for trouble that I've seen before include "Difficulty; public disorder" , "Affliction" , "Pains" , "Misfortune" , "Difficulty or inconvenience" .)