Roadie regularly working in concert hall (5)
I believe the answer is:
odeon
'concert hall' is the definition.
(I've seen this before)
'roadie regularly working' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'working' becomes 'on' (on can mean working or activated).
The alternate letters of 'roadie' are 'ode'.
'ode'+'on'='ODEON'
'in' is the link.
(Other definitions for odeon that I've seen before include "Ancient theatre - modern cinema" , "Ancient Greek building for music" , "Hal" , "Ancient Greek concert hall" , "Do one (anag)" .)