Thanks for the kiss, but there's still something to pay (3)

I believe the answer is:
tax
'there's still something to pay' is the definition.
I can't judge whether this definition defines the answer.
'thanks for the kiss' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'for' says to put letters next to each other.
'the kiss' becomes 'x' (X can represent a kiss).
'ta'+'x'='TAX'
'but' acts as a link.
Can you help me to learn more?
(Other definitions for tax that I've seen before include "Strain; levy" , "Put pressure on like Revenue Commissioners?" , "Payment to the Exchequer" , "Overburden with levy?" , "State levy" .)
