Fixed and definitive (4,3,4)
I believe the answer is:
hard and fast
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fixed and definitive</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for hard and fast that I've seen before include "Not moving" , "(Of rules) unalterable" , "Fixed and definitive" , "Strict" , "like a cannonball" .)