Be servile (6)
I believe the answer is:
kowtow
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">be servile</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 kowtow that I've seen before include "Chinese submissive gesture" , "Lick someone's boots" , "Toady" , "Grovel in old Peking" , "Gesture of submission" .)