Confident fool shamefaced about United (7)
I believe the answer is:
assured
'confident' is the definition.
('assured' can be similar in meaning to 'confident')
'fool shamefaced about united' is the wordplay.
'fool' becomes 'ass' (ass is a kind of fool**).
'shamefaced' becomes 'red'.
'about' says to put letters next to each other.
'united' becomes 'u'.
'red' after 'u' is 'ured'.
'ass'+'ured'='ASSURED'
(Other definitions for assured that I've seen before include "Exhibiting confidence" , "Sad ruse (anag.)" , "Confident, secure" , "Confident - certain" , "Self-confident" .)