Theatre guide (5)
(Other definitions for usherette that I've seen before include "Cinema employee" , "Person showing people to their seats" , "Lady who shows you to your seat in cinema or theatre" , "Girl guide" , "Cinema attendant" .)
'theatre guide' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for usher that I've seen before include "Theatre assistant" , "whose house collapsed?" , "Person showing one to a seat" , "One conducts people to seats" , "Theatre attendant" .)