Single queen needed after good start (7)
I believe the answer is:
pioneer
'start' is the definition.
(thesaurus)
'single queen needed after good' is the wordplay.
'single' becomes 'one' (synonyms).
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'needed after' says to put letters next to each other.
'good' becomes 'pi' (I've seen this in other clues).
'one'+'er'='oneer'
'oneer' after 'pi' is 'PIONEER'.
(Other definitions for pioneer that I've seen before include "true original" , "make the first move!" , "take the lead" , "original leader" , "Ripe one (anag.)" .)