Taxing with respect to converted euros (7)
I believe the answer is:
onerous
'taxing' is the definition.
(I know that taxing can be written as onerous)
'with respect to converted euros' is the wordplay.
'with respect to' becomes 'on'.
'converted' indicates anagramming the letters.
'euros' anagrammed gives 'erous'.
'on'+'erous'='ONEROUS'
(Other definitions for onerous that I've seen before include "Involving much effort" , "quite a burden if so" , "Burdensome, demanding" , "'Heavy, burdensome (7)'" , "No euros? That's burdensome" .)