Levels site from seventies (5)
I believe the answer is:
evens
'levels' is the definition.
('even' can be a synonym of 'level')
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for evens that I've seen before include "Exchange, substitute" , "Bookies' odds matching the amount staked" , "Quits" , "These are odds, strangely" , "Balanced odds" .)