Remedy almost certain to produce riches (8)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
treasure
'riches' is the definition.
(treasure is a kind of riches)
'remedy almost certain' is the wordplay.
'remedy' becomes 'treat'.
'almost' means to remove the last letter (most of the word but not all of it).
'certain' becomes 'sure' (similar in meaning).
'treat' with its final letter taken away is 'trea'.
'trea'+'sure'='TREASURE'
'to produce' acts as a link.
(Other definitions for treasure that I've seen before include "Hold dear, prize" , "Very valuable object" , "Accumulated wealth, could be buried" , "Cherish like heap of valuables" , "Value highly" .)