Way to maintain high score, flashy system? (5,4)
I believe the answer is:
morse code
'flashy system?' is the definition.
(system involving flashing lights)
'way to maintain high score' is the wordplay.
'way' becomes 'mode' (synonyms).
'to maintain' means one lot of letters goes inside another (maintain can mean to keep or preserve).
'high' indicates anagramming the letters (can mean drunk or on drugs and hence disordered).
'score' with letters rearranged gives 'orsec'.
'mode' going around 'orsec' is 'MORSE CODE'.
(Other definitions for morse code that I've seen before include "Means of signalling by dots and dashes" , "A way to signal" , "Dots and dashes alphabet" , "Means to communicate" , "Dot-dash signalling" .)