Steady girlfriend who may be a Londoner (6)

I believe the answer is:

sedate

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'steady girlfriend who may be a londoner' is the definition.
'sedate' can be an answer for 'steady' (thesaurus). I am not certain of the remainder of the definition.

'steady girlfriend' is the wordplay.
'steady' becomes 'se' (I can't justify this - if you can you should believe this answer much more).
'girlfriend' becomes 'date' (date can mean someone you are dating).
'se'+'date'='SEDATE'

Can you help me to learn more?

(Other definitions for sedate that I've seen before include "boring" , "Calm - staid" , "Staid; put to sleep" , "Calm or spectral appartition" , "Dignified and subdued" .)

I've seen this clue in The Independent.

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