Tired of being cautious about middle-men (5)
I believe the answer is:
weary
'tired of' is the definition.
(thesaurus)
'cautious about middle-men' is the wordplay.
'cautious' becomes 'wary' (similar in meaning).
'about' means one lot of letters goes inside another.
'middle' indicates the central letters.
The middle of 'men' is 'e'.
'wary' going around 'e' is 'WEARY'.
'being' is the link.
(Other definitions for weary that I've seen before include "Tired - bored" , "Whacked" , "flag" , "Worn-out" , "Physically and mentally fatigued" .)