Where Cook encountered queen's WWI recruiting officer? (9)
I believe the answer is:
kitchener
'wwi recruiting officer?' is the definition.
(figure from 'your country needs you' poster)
'where cook encountered queen's' is the wordplay.
'where cook encountered' becomes 'kitchen' (a cook works in a kitchen).
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'kitchen'+'er'='KITCHENER'
(Other definitions for kitchener that I've seen before include "'Your country needs you' soldier" , "Army leader" , "British field marshall, whose image appeared on WWI recruitment posters" , "wartime leader" , "cooker" .)