Poet Khayyam (4)
I believe the answer is:
omar
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">poet khayyam</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for omar that I've seen before include "Arab" , "- Khayyam, Pers. poet" , "old poet" , "and 16 Down: Persian poet" , "- Khayyam, Persian poet, astronomer and mathematician" .)