Inflexible, strict (4,3,4)
I believe the answer is:
hard and fast
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">inflexible</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">strict</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that strict can be written as hard-and-fast)</span><br/ ><br/ ></span>
(Other definitions for hard and fast that I've seen before include "(Of rules) invariable" , "Strict" , "Stupid person" , "like a cannonball" , "Not moving" .)