Queen bearing grand letters exits (8)
I believe the answer is:
egresses
'exits' is the definition.
(egress means an exit)
'queen bearing grand letters' is the wordplay.
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'bearing' is an insertion indicator.
'grand' becomes 'g' (G is short for grand as in a thousand).
'letters' becomes 'esses' (more than one S).
'er' enclosing 'g' is 'egr'.
'egr'+'esses'='EGRESSES'
(Other definitions for egresses that I've seen before include "Actions of going out" , "Exits, ways out" .)