Moves queen up - vulnerable castle takes nothing (9)
I believe the answer is:
relocates
'moves' is the definition.
(I know this)
'queen up vulnerable castle takes nothing' is the wordplay.
'queen' becomes 'er' (abbreviation for Elizabeth Regina).
'up' is a reversal indicator (in down clue: letters go upwards).
'vulnerable' indicates an anagram (the letters are vulnerable to change).
'takes' says to put letters next to each other.
'nothing' becomes 'O' (looks like zero - 0).
'er' reversed gives 're'.
'castle'+'o'='castleo'
'castleo' anagrammed gives 'locates'.
're'+'locates'='RELOCATES'
(Another definition for relocates that I've seen is " Moves".)