Tire pressure indicator (5)
I believe the answer is:
gauge
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tire pressure indicator</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for gauge that I've seen before include "Measure - estimate" , "Distance between the rails of a railway track" , "Measuring instrument" , "Meter" , "Measure against a standard" .)