Sort of test papers getting a 100 (4)
I believe the answer is:
acid
'sort of test' is the definition.
'acid' can be an answer for 'test' (thesaurus). I am not sure about the 'sort of' bit.
'papers getting a 100' is the wordplay.
I cannot really understand how this works, but
'papers' could be 'id' (identification papers) and 'id' is found in the answer.
'a' is present in the answer.
'100' could be 'c' (Roman numeral) and 'c' is present 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 acid that I've seen before include "Sour - sharp" , "Caustic liquid of many kinds" , "- - -drop, sweet" , "Sour - LSD" , "scathing" .)