Sample a slice of white sturgeon (4)
I believe the answer is:
test
'sample' is the definition.
(I've seen this in another clue)
'a slice of white sturgeon' is the wordplay.
'a slice of' indicates the answer is hidden within the clue.
'TEST' is hidden within 'white sturgeon'.
(Other definitions for test that I've seen before include "Short exam" , "criterion" , "Examine to play international cricket match" , "Ward off" , "water flowing through Hampshire" .)