Water shaft has a tight tin lid that's intended to be helpful (4-5)
I believe the answer is:
well-meant
'intended to be helpful' is the definition.
'water shaft has a tight tin lid' is the wordplay.
I cannot really see how this works, but
'water' could be 'well' (well water is a kind of water) and 'well' is present in the answer.
'a' could be 'an' and 'an' is found in the answer.
The remaining letters 'met' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'that's' is the link.
Can you help me to learn more?
(Other definitions for well-meant that I've seen before include "Done with good intentions but poor result" , "Kind" .)