Brief period (5)
'brief period' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for spell that I've seen before include "Stretch" , "Magical charm; short time" , "... mean" , "get letters in order" , "Name letters of a word" .)
(Other definitions for stint that I've seen before include "Brief spell" , "Stretch; be miserly" , "Be niggardly with tints" , "Unbroken period during which you do one thing" , "Stretch of work" .)