Regularly target a certain prize (8)
I believe the answer is:
treasure
'prize' is the definition.
(I know that prize can be written as treasure)
'regularly target a certain' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'certain' becomes 'sure' (synonyms).
The alternate letters of 'target' are 'tre'.
'tre'+'a'+'sure'='TREASURE'
(Other definitions for treasure that I've seen before include "Quantity of precious objects" , "X marks its spot!" , "Value highly" , "Valuable hoard" , "Very valuable object" .)