Litter left in boat (7)
I believe the answer is:
clutter
'litter left in boat' is the definition.
'clutter' can be an answer for 'litter' (thesaurus). I am not certain of the 'left in boat' bit.
'litter left in boat' is the wordplay.
'litter left' becomes 'l' (common abbreviation. I am not sure about the 'litter' bit.).
'in' means one lot of letters goes inside another.
'boat' becomes 'cutter' (historical type of ship).
'l' inserted into 'cutter' is 'CLUTTER'.
Can you help me to learn more?
(Other definitions for clutter that I've seen before include "Confused mess" , "Confusion" , "Disorderly mess" , "Untidy lot of objects in room" , "Untidy mess" .)