Lesson hammered out amidst test (8)
I believe the answer is:
tutorial
'lesson' is the definition.
(I've seen this before)
'hammered out amidst test' is the wordplay.
'hammered' indicates an anagram (I've seen this in other clues).
'amidst' indicates putting letters inside.
'test' becomes 'trial' ('trial' can be a synonym of 'test').
'out' anagrammed gives 'uto'.
'uto' inserted within 'trial' is 'TUTORIAL'.
(Other definitions for tutorial that I've seen before include "Study meeting" , "Period of teaching as from college lecturer" , "Private lesson" , "Seminar" , "Session of intensive teaching to an individual or small group" .)