I speak angrily about working for a period of time (4,3)
I believe the answer is:
iron age
'a period of time' is the definition.
(I know that Iron Age is a period of time)
'i speak angrily about working' is the wordplay.
'speak angrily' becomes 'rage' (I am not sure about this - if you are sure you should believe this answer much more).
'about' indicates putting letters inside.
'working' becomes 'on' (on can mean working or activated).
'rage' going around 'on' is 'ronage'.
'i'+'ronage'='IRON AGE'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for iron age that I've seen before include "prehistoric times" , "It followed the Bronze Age" , "A region (anag) - period long ago" , "Period from about 1100 BC" , "Period in the history of man - a region (anag)" .)