Time learner in onerous task — and chuckle gleefully (7)
I believe the answer is:
chortle
'chuckle gleefully' is the definition.
(I've seen this before)
'time learner in onerous task' is the wordplay.
'time' becomes 't'.
'learner' becomes 'l'.
'in' is an insertion indicator.
'onerous task' becomes 'chore' (I've seen this before).
't'+'l'='tl'
'tl' inserted within 'chore' is 'CHORTLE'.
'and' is the link.
(Other definitions for chortle that I've seen before include "Laugh gleefully" , "Chuckle gleefully" , "Chuckle merrily" , "Loud gleeful chuckle" , "Noisy gleeful laugh" .)