Substitute held by players at Zurich (6)
I believe the answer is:
ersatz
'substitute' is the definition.
('ersatz' can be a synonym of 'substitute')
'held by players at zurich' is the wordplay.
'held by' indicates a hidden word.
'ERSATZ' is hidden within 'players at zurich'.
(Other definitions for ersatz that I've seen before include "Artificial, imitation - from German" , "inferior type" , "Made in imitation, from German" , "Artificial or synthetic, from German" , "Artificial or inferior imitation" .)