Barrow boy is quiet at dawn (6)

I believe the answer is:
pearly
'quiet at dawn' is the definition.
'pearly' can be an answer for 'quiet' (thesaurus). I am not sure about the 'at dawn' bit.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for pearly that I've seen before include "like a king in East London?" , "Like the gates of heaven?" , "Like heaven's gates?" , "Substance of heaven's gates" , "to reach such gates, one'll be late" .)
