Tire pressure checker (5)
I believe the answer is:
gauge
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tire pressure checker</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for gauge that I've seen before include "Measuring instrument" , "Instrument to measure or test" , "Measure(r)" , "Distance between the rails of a railway track" , "Measuring device" .)