In all likelihood, supporting learner in child (8)
I believe the answer is:
'in all likelihood' is the definition.
('probably' can be a synonym of 'in all likelihood')
'supporting learner in child' is the wordplay.
I cannot really understand how this works, but
'supporting' could be 'pro' (I've seen this in other clues) and 'pro' is located in the answer.
'learner' could be 'l' and 'l' is found in the answer.
'child' could be 'baby' (baby is a kind of child) and 'baby' is found within the leftover letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for probably that I've seen before include "I expect so" , "Most possibly" , "Likely" , "In all likelihood" , "Almost certainly" .)