Additional working hours in public institutions, maybe excessive at first (8)
I believe the answer is:
overtime
'additional working hours' is the definition.
The answer and definition can be both related to time as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'public institutions maybe excessive at first' is the wordplay.
'public' becomes 'overt' (both can mean well-known or unconcealed).
'at first' says to take the initial letters.
The initial letters of 'institutions maybe excessive' is 'ime'.
'overt'+'ime'='OVERTIME'
'in' is the link.
Can you help me to learn more?
(Other definitions for overtime that I've seen before include "Work in excess of fixed period" , "Work outside normal hours" , "Hours worked in excess of usual" , "Pay for extra work" , "Extra hours (at work)" .)