Basic US rate confused English (7)
I believe the answer is:
austere
'basic' is the definition.
(thesaurus)
'us rate confused english' is the wordplay.
'confused' is an anagram indicator.
'english' becomes 'e' (abbreviation).
'us'+'rate'='usrate'
'usrate' is an anagram of 'auster'.
'auster'+'e'='AUSTERE'
(Other definitions for austere that I've seen before include "'Spartan, simple (7)'" , "Strict in appearance" , "Severe, ascetic" , "Grim -- a US tree (anag)" , "not of luxury type" .)