It's powerless, even to sink! (4)
I believe the answer is:
raft
'sink' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'it's powerless even' is the wordplay.
I cannot really see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found within the answer.
The remaining letters 'raf' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'to' acts as a link.
Can you help me to learn more?
(Other definitions for raft that I've seen before include "Floating mass of logs" , "Simple boat" , "Travel on river, in a way" , "Flat floating craft" , "Structure that floats" .)