A levy on tacks? (3)
I believe the answer is:
tax
'a levy' is the definition.
(tax is a kind of levy)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for tax that I've seen before include "VAT or DIRT, say" , "Strain - duty" , "Overburden with levy?" , "Are demanding" , "Demand" .)