Asian vessel a mile in length (6)
I believe the answer is:
sampan
'asian vessel' is the definition.
'sampan' can be an answer for 'vessel' (sampan is a kind of vessel). I am unsure of the 'asian' bit.
'a mile in length' is the wordplay.
'mile' becomes 'm' (common abbreviation).
'in' is an insertion indicator.
'length' becomes 'span' (I've seen this in another clue).
'a'+'m'='am'
'am' going into 'span' is 'SAMPAN'.
Can you help me to learn more?
(Other definitions for sampan that I've seen before include "Flat-bottomed Chinese skiff" , "Small Asian rowing boat" , "oriental vessel" , "Small oriental rowing boat" , "Boat in Far East" .)