Two players about to strike ball on table (5)
I believe the answer is:
white
'ball on table' is the definition.
(eg white ball in snooker)
'two players about to strike' is the wordplay.
'two players' becomes 'WE' (West and East are players in the card game bridge).
'about' is an insertion indicator.
'to strike' becomes 'hit' ('hit' can be a synonym of 'strike').
'we' enclosing 'hit' is 'WHITE'.
(Other definitions for white that I've seen before include "Covered in snow" , "See 9" , "Opponent of six dn (chess)" , "Drink that should be chilled" , "Colour of milk" .)