Drag queen where prisoners were held in London (5)
I believe the answer is:
tower
'where prisoners were held in london' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'drag queen' is the wordplay.
'drag' becomes 'tow' (towing is a kind of dragging).
'queen' becomes 'ER' (short for Elizabeth Regina ie Queen Elizabeth).
'tow'+'er'='TOWER'
Can you help me to learn more?
(Other definitions for tower that I've seen before include "Turret" , "One to pull" , "Wrote (anag.)" , "Drawer" , "Perhaps keep" .)