Ship's wreckage — beginning to find plenty in the morning (7)
I believe the answer is:
flotsam
'ship's wreckage' is the definition.
(flotsam is wreckage or debris from a ship)
'beginning to find plenty in the morning' is the wordplay.
'beginning to' indicates taking the first letters.
'plenty' becomes 'lots' (I've seen this before).
'in the morning' becomes 'am' (AM on a clock).
The first letter of 'find' is 'f'.
'f'+'lots'+'am'='FLOTSAM'
(Other definitions for flotsam that I've seen before include "Rubbish on sea" , "The floating wreckage of a ship" , "Washed-up wreckage" , "Detritus" , "Wreckage found floating" .)