Compound tax for dummies? (7)
I believe the answer is:
nitrate
'compound' is the definition.
(nitrate is a kind of compound)
'tax for dummies?' is the wordplay.
'tax' becomes 'rate' (rate is a kind of tax).
'for' is a charade indicator (letters next to each other) (I've seen this in other clues).
'dummies?' becomes 'nit' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'rate' after 'nit' is 'NITRATE'.
Can you help me to learn more?
(Other definitions for nitrate that I've seen before include "Fertiliser chemical" , "Tear tin up for fertiliser" , "following 28 [SILVER]" , "Nattier (anag.)" , "salt" .)