Junk initially found almost at sea (7)
I believe the answer is:
flotsam
'junk' is the definition.
(thesaurus)
'initially found almost at sea' is the wordplay.
'initially' suggests taking the first letters.
'at sea' is an anagram indicator.
The first letter of 'found' is 'f'.
'almost' anagrammed gives 'lotsam'.
'f'+'lotsam'='FLOTSAM'
(Other definitions for flotsam that I've seen before include "Things going adrift" , "Wreckage found floating" , "Things found floating from a ship" , "Goods lost" , "The floating wreckage of a ship" .)