From memory (2,5)
I believe the answer is:
by heart
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">from memory</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 by heart that I've seen before include "Committed to memory" , "(Learnt) in memory" , "One way to remember" , "Parrot-fashion" , "how circulation is maintained" .)