After time more unusual accepted learner’s young child (7)
I believe the answer is:
toddler
'young child' is the definition.
(I've seen this before)
'after time more unusual accepted learner's' is the wordplay.
'after' means one lot of letters go next to another.
'time' becomes 't' (abbreviation).
'more unusual' becomes 'odder' ('odd' can be similar in meaning to 'unusual').
'accepted' means one lot of letters goes inside another.
'learner' becomes 'l'.
'odder' placed around 'l' is 'oddler'.
't' next to 'oddler' is 'TODDLER'.
(Other definitions for toddler that I've seen before include "One beginning to walk" , "Young walker" , "Feeble walker" , "Little one" , "Child just learning to walk" .)