Being good, a lapse arising in class initially ignored (8)
I believe the answer is:
organism
'being' is the definition.
(I know that being can be written as organism)
'good a lapse arising in class initially ignored' is the wordplay.
I cannot really see how this works, but
'good' could be 'g' (abbreviation) and 'g' is present in the answer.
'a' could be 'an' and 'an' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for organism that I've seen before include "Body - cell - Mao grins (anag)" , "Living animal or vegetable" , "Living thing -- man's giro (anag)" , "individual creation" , "Living animal or plant" .)