Former statute, correct in every detail (5)
I believe the answer is:
exact
'correct in every detail' is the definition.
(exactly right)
'former statute' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'statute' becomes 'act' (an act of law).
'ex'+'act'='EXACT'
(Other definitions for exact that I've seen before include "As a right, demand" , "Spot-on" , "correct in every detail" , "totally accurate" , "without rounding" .)