Nine-to-five, say, when allowance is curtailed (5)
I believe the answer is:
ratio
'nine-to-five say' is the definition.
I can't judge whether this defines the answer.
'allowance is curtailed' is the wordplay.
'allowance' becomes 'ration' (I've seen this before).
'is curtailed' means to remove the last letter.
'ration' with its final letter removed is 'RATIO'.
'when' is the link.
Can you help me to learn more?
(Other definitions for ratio that I've seen before include "Mathematical relationship" , "Relative magnitude" , "Proportional relationship" , "9 to 5, say?" , "Relation between two things, numbers say" .)