Clear, the Queen's jockey (5)
I believe the answer is:
rider
'jockey' is the definition.
(thesaurus)
'clear the queen's' is the wordplay.
'clear' becomes 'rid' ('rid' can be a synonym of 'clear'**).
'the queen' becomes 'er' (Elizabeth Regina).
'rid'+'er'='RIDER'
(Other definitions for rider that I've seen before include "one making journey" , "Jury's recommendation" , "Passenger" , "Supplement to verdict" , "One on horse or bike" .)