At home with water, say, lacking money (9)
I believe the answer is:
insolvent
'lacking money' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'at home with water' is the wordplay.
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'with' says to put letters next to each other.
'water' becomes 'solvent' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in'+'solvent'='INSOLVENT'
'say' is the link.
Can you help me to learn more?
(Other definitions for insolvent that I've seen before include "gone to the wall" , "on the rocks" , "Snivel not, although you are bankrupt!" , "strapped for cash" , "without the means to pay" .)