Congenial diner fly worried (8)
I believe the answer is:
friendly
'congenial' is the definition.
('friendly' is associated in meaning with 'congenial')
'diner fly worried' is the wordplay.
'worried' is an anagram indicator.
'diner'+'fly'='dinerfly'
'dinerfly' with letters rearranged gives 'FRIENDLY'.
(Other definitions for friendly that I've seen before include "Well-disposed" , "One is obviously on good terms with" , "such a society" , "Amicable and kindly" , "prepared to talk to fellow passengers?" .)