Primates turn up for allowance detachment (10)
I believe the answer is:
separation
'detachment' is the definition.
('separation' can be a synonym of 'detachment')
'primates turn up for allowance' is the wordplay.
'primates' becomes 'apes' (ape is a kind of primate).
'turn up' says the letters should be written in reverse.
'for' means one lot of letters go next to another.
'allowance' becomes 'ration' (I've seen this before).
'apes' in reverse letter order is 'sepa'.
'sepa'+'ration'='SEPARATION'
(Other definitions for separation that I've seen before include "divorce" , "Detachment" , "Split" , "Break-up" , "Disunion" .)