Examination for all? Not entirely (4)
I believe the answer is:
oral
'examination' is the definition.
(oral is a kind of examination)
'for all? not entirely' is the wordplay.
'not entirely' indicates the answer is hidden within the clue.
'ORAL' can be found hidden inside 'for all'.
(Other definitions for oral that I've seen before include "Type of exam" , "Spoken rather than written" , "language exam" , "'Spoken, not written (4)'" , "Unwritten examination" .)