Memorise (5)
I believe the answer is:
learn
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">memorise</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for learn that I've seen before include "teach illiterate" , "Acquire 28 across" , "Master" , "Comprehend" , "Study (at school?)" .)