Symbol of happiness (8)
I believe the answer is:
bluebird
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">symbol of happiness</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 bluebird that I've seen before include "American member of thrush family (seen over Dover?)" , "Name of the cars and boats in which Malcolm and Donald Campbell set land and water speed records" , "Cerulean flier associated with happiness" , "Donald Campbell's speedboat - relative of thrush" , "symbol of happiness" .)