Dining out with worker up in arms (9)
I believe the answer is:
indignant
'up in arms' is the definition.
(I've seen this before)
'dining out with worker' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'with' means one lot of letters go next to another.
'worker' becomes 'ant' (worker is a type of ant).
'dining' anagrammed gives 'indign'.
'indign'+'ant'='INDIGNANT'
(Other definitions for indignant that I've seen before include "somewhat angry" , "feeling anger" , "Somewhat outraged" , "Anger at having been treated unjustly" , "Annoyed at unfair treatment" .)