Of short duration (5)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">of short duration</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for brief that I've seen before include "Short or concise" , "Terse" , "Document stating the facts of a legal case" , "Succinct" , "Ephemeral" .)
(Other definitions for transitory that I've seen before include "Passing" , "Ephemeral" , "Here-today-gone-tomorrow" , "Short-lived" , "Fleeting" .)
(Other definitions for transient that I've seen before include "gone in a trice!" , "Ephemeral" , "Fleeting" , "fugitive" , "Lasting little time" .)