Assemble Mercedes securing badge (6)
I believe the answer is:
emblem
'badge' is the definition.
(thesaurus)
'assemble mercedes securing' is the wordplay.
'securing' indicates a hidden word.
'EMBLEM' is hidden within 'assemble mercedes'.
(Other definitions for emblem that I've seen before include "Symbol, representing a country say" , "Badge, token" , "Logo" , "Symbolic object" , "Badge or representative device" .)