Hard worker, German, carrying floating structure (7)
I believe the answer is:
grafter
'hard worker' is the definition.
(I've seen this before)
'german carrying floating structure' is the wordplay.
'german' becomes 'ger' (abbreviation).
'carrying' means one lot of letters goes inside another.
'floating structure' becomes 'raft' (I've seen this before).
'ger' placed around 'raft' is 'GRAFTER'.
(Other definitions for grafter that I've seen before include "One who works hard" , "Hard worker - corrupt operator" .)