Supply zero input for taxing (5)
I believe the answer is:
hoard
'supply' is the definition.
(I've seen this before)
'zero input for taxing' is the wordplay.
I cannot really see how this works, but
'zero' could be 'o' (O resembles 0) and 'o' is present in the answer.
The remaining letters 'hard' 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).
Can you help me to learn more?
(Other definitions for hoard that I've seen before include "keep in reserve" , "Accumulate" , "Store, usually hidden" , "Secret store of valuables" , "Reserve supply" .)