A measure of how light is modestly occluded (6)

I believe the answer is:

bushel

I'm a little stuck... Click here to teach me more about this clue!

'a measure' is the definition.
(bushel is a kind of measure)

I don't understand the remainder of the clue.

(Other definitions for bushel that I've seen before include "Dry measure of eight gallons" , "Old measure of volume" , "Old measure of capacity" , "A few pecks wanted" , "Obsolete measure (equal to 8 gallons)" .)

I've seen this clue in The Irish Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.