That woman behind us is a theatre attendant (5)
I believe the answer is:
usher
'a theatre attendant' is the definition.
(an usher shows members of an audience to seats)
'that woman behind us' is the wordplay.
'that woman' becomes 'her' (her refers to a woman).
'behind' means one lot of letters go next to another.
'her' after 'us' is 'USHER'.
'is' acts as a link.
(Other definitions for usher that I've seen before include "One who should lead the way" , "Cinema or wedding attendant" , "Theatre/cinema worker" , "Cinema or wedding official" , "He shows people to their seats in theatre" .)