Precise court overturning dismissal at first (5)
I believe the answer is:
exact
'precise' is the definition.
('exact' is associated in meaning with 'precise')
'court overturning dismissal at first' is the wordplay.
'court' becomes 'ct'.
'overturning' shows that the letters should be reversed in order.
'dismissal' becomes 'axe'.
'at first' is a charade indicator (letters next to each other).
'axe' backwards is 'exa'.
'ct' after 'exa' is 'EXACT'.
(Other definitions for exact that I've seen before include "Absolutely accurate or correct" , "Precise and strictly correct" , "correct in every detail" , "Rigorous" , "Absolutely right" .)