Brief spark for a shiner (4)
I believe the answer is:
star
'shiner' is the definition.
(I've seen this in another clue)
'brief spark' is the wordplay.
'brief' means to remove the last letter (a shorter or briefer version of the word).
'spark' becomes 'start' (spark can mean to trigger or start).
'start' with its last letter taken away is 'STAR'.
'for a' acts as a link.
(Other definitions for star that I've seen before include "A heavenly body or film favourite" , "Point of light in the heavens" , "virtuoso" , "Eg, Antares" , "See 5" .)