Cash allowance to be decided by beginning of week, ok to go back outside (8,5)
I believe the answer is:
spending money
'cash allowance' is the definition.
(allowance of money for spending)
I don't understand how the remainder of the clue works.
(Other definitions for spending money that I've seen before include "Cash in your pocket" , "Cash to use for retail therapy?" , "Allowance for small personal expenses" , "Child's weekly allowance" .)