Such men may take turns as openers (3)
I believe the answer is:
key
'such' is the definition.
Both the definition and answer are adjectives. Perhaps there's an association between them I don't understand?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for key that I've seen before include "Scale system for music" , "Eg, Ctrl, Alt or Esc" , "Device for lock" , "It can open" , "Of crucial importance" .)