No working period; time for lunch? (7)
I believe the answer is:
noonday
'time for lunch?' is the definition.
(lunch is often eaten at noon)
'no working period' is the wordplay.
'working' becomes 'on' (on can mean working or activated).
'period' becomes 'day' (day is a kind of period).
'no'+'on'+'day'='NOONDAY'
(Other definitions for noonday that I've seen before include "heat?" , "12 o'clock" , "when sun is hottest" , "Midday, 12p.m." , "Twelve a.m." .)