Prisoner with name sewn in stockings (7)
I believe the answer is:
hostage
'prisoner' is the definition.
(hostage is a kind of prisoner)
'with name sewn in stockings' is the wordplay.
'with' indicates putting letters inside.
'name' becomes 'tag' (I've seen this in other clues).
'sewn in stockings' becomes 'hose' (I can't justify this - if you can you should believe this answer much more).
'tag' put into 'hose' is 'HOSTAGE'.
Can you help me to learn more?
(Other definitions for hostage that I've seen before include "Captive held for ransom" , "Person taken as security" , "One held captive" , "She-goat (anag)" , "person captive to fortune" .)