A bit of light about right for marshal (5)
I believe the answer is:
array
'for marshal' is the definition.
(I've seen this before)
'a bit of light about right' is the wordplay.
'a bit of light' becomes 'ray' (I've seen this in another clue).
'about' means one lot of letters go next to another.
'right' becomes 'ar' (I've seen this in other clues).
'ray' after 'ar' is 'ARRAY'.
(Other definitions for array that I've seen before include "Impressive display or range of something" , "An imposing series or display" , "Matrix; arrange" , "Fine assortment" , "Imposing assembly" .)