US lawyer to call for defiance (6)
I believe the answer is:
daring
'defiance' is the definition.
(thesaurus)
'us lawyer to call' is the wordplay.
'us lawyer' becomes 'DA' (abbreviation for District Attorney).
'to call' becomes 'ring' ('ring' can be a synonym of 'call').
'da'+'ring'='DARING'
'for' is the link.
(Other definitions for daring that I've seen before include "Boldness" , "Audacious, bold" , "'Adventurous, bold (6)'" , "A grind (anag.)" , "Bold, willing to take chance" .)