Hard to leave boat looking shabby (5)
I believe the answer is:
dingy
'looking shabby' is the definition.
'hard to leave boat' is the wordplay.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'to leave' indicates named letters should be taken away.
'boat' becomes 'dinghy' (type of boat).
'dinghy' with 'h' taken away is 'DINGY'.
(Other definitions for dingy that I've seen before include "Dim" , "Dark, grubby" , "Dismal" , "Drab and depressing" , "Dark and rather dirty" .)