Small boat, early in the day, going through bridge (6)
I believe the answer is:
sampan
'small boat' is the definition.
(I know that sampan is a type of skiff)
'early in the day going through bridge' is the wordplay.
'early in the day' becomes 'am' (I can't justify this - if you can you should give a lot more credence to this answer).
'going through' indicates putting letters inside.
'bridge' becomes 'span' (synonyms).
'am' put within 'span' is 'SAMPAN'.
Can you help me to learn more?
(Other definitions for sampan that I've seen before include "Boat in Far East" , "oriental vessel" , "Small 10 boat" , "East Asian boat" , "Small oriental rowing boat" .)