Mandarin tests actor Thurman (7)
I believe the answer is:
satsuma
'mandarin' is the definition.
(I know that satsuma is a type of mandarin)
'tests actor thurman' is the wordplay.
I cannot quite understand how this works, but
'tests' could be 'sats' (american school tests) and 'sats' is present in the answer.
'thurman' could be 'uma' (I've seen this in another clue) and 'uma' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for satsuma that I've seen before include "Variety of tangerine" , "Japanese province and small orange" , "sort of orange" , "As a must (anag)" , "that is easily uncovered" .)