I (6)
I believe the answer is:
myself
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">i</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that i can be written as myself)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for myself that I've seen before include "Crossword compiler" , "Me, in person" , "Reflexive pronoun" , "I personally" , "Emphatically, me" .)