River dividing Upper Vaal evenly has fast current (9)
I believe the answer is:
prevalent
'current' is the definition.
('prevalent' can be similar in meaning to 'current')
'river dividing upper vaal evenly has fast' is the wordplay.
'river' becomes 'r'.
'dividing' indicates putting letters inside.
'evenly' means one should take alternating letters (even-numbered letters only).
'has' is a charade indicator (letters next to each other).
'fast' becomes 'lent' (I've seen this before).
'upper'+'vaal'='uppervaal'
The alternate letters of 'uppervaal' are 'peva'.
'r' inserted inside 'peva' is 'preva'.
'preva'+'lent'='PREVALENT'
(Other definitions for prevalent that I've seen before include "Widely accepted" , "Widespread - current" , "Common" , "powerful" , "general" .)