Turner in hall at Henley (5)
I believe the answer is:
lathe
'turner' is the definition.
(a lathe is something which 'turns')
'in hall at henley' is the wordplay.
'in' indicates a hidden word.
'LATHE' can be found hidden inside 'hall at henley'.
(Other definitions for lathe that I've seen before include "piece of machinery" , "Revolver" , "Turning instrument" , "Wood-shaping machine" , "Machine for cutting, drilling or polishing" .)