Enid ordered form right bistro (5)
I believe the answer is:
diner
'bistro' is the definition.
(thesaurus)
'enid ordered form right' is the wordplay.
I cannot really understand how this works, but
an anagram of 'enid' is 'dine' which is within the answer.
'right' could be 'r' (common abbreviation) and 'r' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for diner that I've seen before include "US eatery" , "Small US restaurant" , "American restaurant" , "Buffet car" , "one at banquet?" .)