New rate certain for wealth (8)
I believe the answer is:
treasure
'for wealth' is the definition.
(treasure is a kind of wealth)
'new rate certain' is the wordplay.
'new' is an anagram indicator.
'certain' becomes 'sure' (synonyms).
'rate' with letters rearranged gives 'trea'.
'trea'+'sure'='TREASURE'
(Other definitions for treasure that I've seen before include "Store of valuables" , "Highly prized possession" , "Cherish like heap of valuables" , "Valued possession, buried perhaps" , "' - - Island' novel" .)