Confident when sued about banker's end (7)
I believe the answer is:
assured
'confident' is the definition.
(similar in meaning)
'when sued about banker's end' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'about' means one lot of letters goes inside another.
'end' says to take the final letters.
The last letter of 'banker' is 'r'.
'sued' placed around 'r' is 'sured'.
'as'+'sured'='ASSURED'
(Other definitions for assured that I've seen before include "Sad ruse (anag.)" , "Self-confident" , "Beyond doubt" , "Secured" , "Gave confidence to" .)