Identified as beauty in youth (8)
I believe the answer is:
labelled
'identified' is the definition.
(I've seen this before)
'beauty in youth' is the wordplay.
'beauty' becomes 'belle' (I've seen this in another clue).
'in' indicates putting letters inside.
'youth' becomes 'lad' (lad means a young man).
'belle' going inside 'lad' is 'LABELLED'.
'as' is the link.
(Other definitions for labelled that I've seen before include "Assigned a category" , "Marked with a tag" , "Identified" , "Described" , "Categorised; tagged" .)