Work appearing in youngster’s website feature (3-2)
I believe the answer is:
pop-up
'website feature' is the definition.
I can't tell whether this definition defines the answer.
'work appearing in youngster's' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'appearing in' is an insertion indicator.
'youngster' becomes 'pup' (a pup is a young dog).
'op' going inside 'pup' is 'POP-UP'.
Can you help me to learn more?
(Other definitions for pop-up that I've seen before include "(Of book) having rising illustrations" , "Three-D picture in book" , "Appear (like toast?)" , "opening quickly but temporarily" , "Appear without warning" .)