Always seeming younger during language lessons? (7)
I believe the answer is:
ageless
'always seeming younger' is the definition.
'during language lessons?' is the wordplay.
'during' indicates the answer is hidden within the clue.
'AGELESS' can be found hidden inside 'language lessons'.
(Other definitions for ageless that I've seen before include "Enduring" , "Never appearing to grow old" , "not appearing to get old" , "Classic" , "Lasting forever" .)