English lesson's ending after teacher turned up (5)
I believe the answer is:
'up' is the definition.
('risen' can be similar in meaning to 'up')
'english lesson's ending after teacher turned' is the wordplay.
'english' becomes 'e' (abbreviation).
'ending' suggests the final letters.
'after' says to put letters next to each other.
'teacher' becomes 'sir' (I've seen this before**).
'turned' says the letters should be written in reverse.
The final letter of 'lesson' is 'n'.
'sir' in reverse letter order is 'ris'.
'en' put after 'ris' is 'RISEN'.
(Other definitions for risen that I've seen before include "Gone up" , "Grown up" , "stirred" , "Increased" , "(Having) come up" .)