Small boat in loosely-drawn image (6)
I believe the answer is:
sketch
'image' is the definition.
(thesaurus)
'small boat' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'boat' becomes 'ketch' (ketch is a kind of sailing vessel).
's'+'ketch'='SKETCH'
'in loosely-drawn' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for sketch that I've seen before include "Basic drawing" , "Slow of understanding" , "Make rough drawing" , "Short humorous scene" , "Brief outline or drawing" .)