Very attentive (3,4)
I believe the answer is:
all ears
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">very attentive</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for all ears that I've seen before include "Prepared to listen" , "description of cornfield?" , ".Listening very intently" , "Very alert" , "Listening attentively" .)