Player's brief decision targets game (5,10)
I believe the answer is:
stage directions
'player's brief' is the definition.
(instructions or brief given to an actor)
'decision targets game' is the wordplay.
'game' is an anagram indicator (solving anagrams is a game).
'decision'+'targets'='decisiontargets'
'decisiontargets' is an anagram of 'STAGE DIRECTIONS'.
(Other definitions for stage directions that I've seen before include "guidance for players" , "Instructions" .)