Irrigate (5)
I believe the answer is:
water
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">irrigate</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for water that I've seen before include "Common liquid" , "Diamond quality" , "What can produce solution" , "Drink - type of 1 across" , "Classical element" .)