Bulgaria's ready to cap variable tax (4)
I believe the answer is:
levy
'tax' is the definition.
(I've seen this in another clue)
'bulgaria's ready to cap variable' is the wordplay.
I cannot quite understand how this works, but
'variable' could be 'y' (algebra) and 'y' is found in the answer.
The remaining letters 'lev' 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).
Can you help me to learn more?
(Other definitions for levy that I've seen before include "draft" , "Raise - army (or money for it)" , "Toll" , "Financial charge" , "Charge imposed and collected" .)