Informal garment (1-5)
I believe the answer is:
t-shirt
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">informal garment</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for t-shirt that I've seen before include "Simple garment" , "Informal collarless top" , "Close-fitting pullover shirt" , "Collarless pullover shirt" , "Pullover top" .)