Arrange letters for a while (5)
I believe the answer is:
spell
This clue is a double definition.
'arrange letters' is the first definition.
(I've seen this in another clue)
'while' is the second definition.
(I've seen this in another clue)
'for a' acts as a link.
(Other definitions for spell that I've seen before include "something to cast" , "Charm; short period" , "Name in order the letters of the alphabet involved" , "Stretch" , "Give out letters" .)