Based on observation (9)
I believe the answer is:
empirical
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">based on observation</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 empirical that I've seen before include "Derived from experience" , "Mail price (anag.)" , "Based on experience or experiment" , "dependent on trial" , "experimental evidence" .)