As a test, there's no longer one at end of term (4)
I believe the answer is:
exam
'as a test' is the definition.
I can't judge whether this defines the answer.
'no longer one at end of term' is the wordplay.
'no longer' becomes 'ex' (prefix meaning former or onetime).
'one' becomes 'a' (a thing is one thing).
'at end of' says to take the final letters.
The final letter of 'term' is 'm'.
'ex'+'a'+'m'='EXAM'
'there's' is the link.
Can you help me to learn more?
(Other definitions for exam that I've seen before include "Formal knowledge test" , "School test (colloq.)" , "One might be taken for English" , "End-of-course assessment" , "One test" .)