Somebody in the theatre when conditions were very primitive (5,3)
I believe the answer is:
stone age
'very primitive' is the definition.
(I've seen this in another clue)
'somebody in the theatre' is the wordplay.
'somebody' becomes 'one' (one can mean some person).
'in the' is an insertion indicator.
'theatre' becomes 'stage' (stage is a kind of theatre).
'one' inserted inside 'stage' is 'STONE-AGE'.
'when conditions were' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for stone age that I've seen before include "Hard time" , "Early epoch when man used pre-metal tools" , "Neolithic" , "before copper came in" , "Old time" .)