Without ceremony, nightdress is trimmed by South Bank playhouse (9)
I believe the answer is:
negligent
'without ceremony nightdress is trimmed by south bank playhouse' is the definition.
I can't tell whether this definition defines the answer.
'without ceremony nightdress is trimmed by' is the wordplay.
'without ceremony' becomes 'nt' (I can't justify this - if you can you should give a lot more credence to this answer).
'nightdress' becomes 'negligee' (I've seen this before).
'is trimmed' means to remove the last letter (the final letter is trimmed off).
'by' says to put letters next to each other.
'negligee' with its final letter removed is 'neglige'.
'nt' put after 'neglige' is 'NEGLIGENT'.
Can you help me to learn more?
(Other definitions for negligent that I've seen before include "Careless, remiss" , "Not taking due care" , "lacking care" , "Lax" , "Careless of duties" .)