Played game, concealing large twinkle (5)
I believe the answer is:
gleam
'twinkle' is the definition.
(I've seen this in another clue)
'played game concealing large' is the wordplay.
'played' indicates anagramming the letters (letters playing around).
'concealing' indicates putting letters inside (back).
'large' becomes 'L' (eg in clothes sizes).
'game' with letters rearranged gives 'geam'.
'geam' enclosing 'l' is 'GLEAM'.
(Other definitions for gleam that I've seen before include "Brief shining" , "Brief show of soft light" , "Flash of light" , "Small stream of light" , "Glimmer, lustre" .)