Quite level, tray I gathered (10)
I believe the answer is:
relatively
'quite' is the definition.
(thesaurus)
'level tray i gathered' is the wordplay.
'gathered' indicates anagramming the letters (the letters are gathered into a new order).
'level'+'tray'+'i'='leveltrayi'
'leveltrayi' anagrammed gives 'RELATIVELY'.
(Other definitions for relatively that I've seen before include "in the family way?" , "Somewhat" .)