Divorcee prompt to accept solicitor's first defence (6)
I believe the answer is:
excuse
'defence' is the definition.
(excuse is a kind of defence)
'divorcee prompt to accept solicitor's first' is the wordplay.
'divorcee' becomes 'ex' (I've seen this in other clues).
'prompt' becomes 'cue' ('cue' can be a synonym of 'prompt').
'to accept' indicates putting letters inside.
'first' says to take the initial letters.
The first letter of 'solicitors' is 's'.
'cue' enclosing 's' is 'cuse'.
'ex'+'cuse'='EXCUSE'
(Other definitions for excuse that I've seen before include "Forgive or overlook an offence" , "Make apologies for" , "Justification for wrongdoing" , "Defence of offensive behaviour" , "Plea; let off" .)