Current success at cards generating belief (5)
I believe the answer is:
islam
'belief' is the definition.
(I know that Islam is a belief)
'current success at cards' is the wordplay.
'current' becomes 'I' (symbol for electric current).
'success at cards' becomes 'slam' (term in the card game bridge).
'i'+'slam'='ISLAM'
'generating' acts as a link.
(Other definitions for islam that I've seen before include "Major world religion" , "Mails to great eastern religion" , "Creed" , "Faith with five pillars" , "Religious faith of Muslims" .)