Mean to ignore learner's unhappiness (6)
I believe the answer is:
misery
'unhappiness' is the definition.
(misery is a kind of unhappiness)
'mean to ignore learner's' is the wordplay.
'mean' becomes 'miserly' (mean can mean miserly or ungenerous).
'to ignore' suggests deleting specific letters.
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'miserly' with 'l' taken out is 'MISERY'.
(Other definitions for misery that I've seen before include "''. . . . . . loves company''" , "Intense unhappiness" , "Great suffering" , "Wretched conditions" , "Despair" .)