Teacher, one with tension after end of term (8)
I believe the answer is:
mistress
'teacher' is the definition.
(mistress is a kind of teacher)
'one with tension after end of term' is the wordplay.
'one' becomes 'i' (Roman numeral).
'with tension' becomes 'stress' (I am not sure about this - if you are sure you should believe this answer much more).
'after' says to put letters next to each other.
'end of' says to take the final letters.
The last letter of 'term' is 'm'.
'i'+'stress'='istress'
'istress' after 'm' is 'MISTRESS'.
Can you help me to learn more?
(Other definitions for mistress that I've seen before include "Bit on the side" , "Lady" , "lover" , "Woman teacher" , "she wears the trousers?" .)