Loaded old boat containing large case (7)
I believe the answer is:
opulent
'loaded' is the definition.
(I've seen this before)
'old boat containing large case' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'boat' becomes 'punt' (I've seen this before**).
'containing' means one lot of letters goes inside another.
'case' means to remove the middle letters.
'large' with its centre taken out is 'le'.
'punt' going around 'le' is 'pulent'.
'o'+'pulent'='OPULENT'
(Other definitions for opulent that I've seen before include "extremely elegant" , "Ostentatiously costly and luxurious" , "Rich, luxuriant" , "Wealthy or lavish" , "Wealthy, luxurious" .)