Tease about lack of youth and bony frame (7)
I believe the answer is:
ribcage
'bony frame' is the definition.
(frame of bones in the body)
'tease about lack of youth' is the wordplay.
'tease' becomes 'rib' (I've seen this before).
'about' becomes 'c' (abbreviation for circa).
'lack of youth' becomes 'age' (age can mean being old or elderly).
'rib'+'c'+'age'='RIBCAGE'
'and' acts as a link.
(Other definitions for ribcage that I've seen before include "(Bones in) chest wall" , "bony frame" , "part of chest" , "organ case" , "skeletal frame" .)