Leg fractured originally: justifiable concern for player
I believe the answer is:
stage fright
'player' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'leg fractured originally justifiable concern' is the wordplay.
'leg' becomes 'stage' ('stage' can be a synonym of 'leg').
'fractured originally justifiable concern' becomes 'fright' (I can't justify this - if you can you should believe this answer much more).
'stage'+'fright'='STAGE-FRIGHT'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for stage fright that I've seen before include "Performer's nervousness" , "Performer's fear" , "problem for players" , "Nervousness in front of audience" , "Panic experienced by performer" .)