Endless tax in most ridiculous time (9)
I believe the answer is:
incessant
'endless' is the definition.
(I've seen this before)
'tax in most ridiculous time' is the wordplay.
I cannot quite see how this works, but
'tax' could be 'cess' (I've seen this in other clues) and 'cess' is located in the answer.
'in' is present in the answer.
'time' could be 't' (abbreviation) and 't' is present in the answer.
The remaining letters 'an' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for incessant that I've seen before include "Ceaseless" , "Since Stan was continual." , "happening all the time" , "without a break" , "Continual and uninterrupted" .)