Arkwright almost reserving room for girl (5)
I believe the answer is:
norma
'for girl' is the definition.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for norma that I've seen before include "Opera - ex-PM's wife" , "name for Monroe" , "Marilyn was properly one" , "Shearer or Major" , "The 'Rule' constellation" .)