Busy bee (5,6)
'busy bee?' is the definition.
(busy bee is a kind of worker)
This is all the clue.
(Other definitions for worker that I've seen before include "See 20" , "Labourer" , "See 1" , "Busy bee" , "See 8" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">busy bee</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for eager beaver that I've seen before include "keen customer" , "Enthusiastic worker" , "Alert and active type?" , "Someone who's (too) enthusiastic about work" , "Diligent worker" .)