Game official (5)
'game official' is the definition.
(short for referee)
This is all the clue.
(Other definitions for ref that I've seen before include "Football's whistler" , "In brief, he controls a soccer match" , "'Game judge, in short (3)'" , "Whistleblower (abbr)" , "Middleman needing cards" .)
(Other definitions for timer that I've seen before include "One may be alarmed" , "hourglass" , "one of 14 [CUCKOO CLOCKS]" , "Stopwatch, say" , "Preset mechanisation to activate a device" .)
'game official' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for scorer that I've seen before include "- e.g. 13 17 for 1A [PORTER-FIELD for SUNDERLAND]" , "Sir, not one without heart as a" , "Film music arranger" , "player achieving a touchdown?" , "Cricket bookkeeper" .)