Urge strongly (6)
I believe the answer is:
exhort
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">urge strongly</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 exhort that I've seen before include "Urge, advise earnestly" , "Give great encouragement to" , "Spur on" , "Urge or advise strongly" , "Call" .)