Nice tax changed as imprecise (7)
I believe the answer is:
inexact
'imprecise' is the definition.
(associated in meaning)
'nice tax changed' is the wordplay.
'changed' indicates anagramming the letters.
'nice'+'tax'='nicetax'
'nicetax' anagrammed gives 'INEXACT'.
'as' acts as a link.
(Other definitions for inexact that I've seen before include "Rough" , "not wholly Right" , "Woolly" , "estimated?" , "Not precise, approximate" .)