What the beefeater renders? (6,7)

I believe the answer is:

yeoman service

I'm a little stuck... Click here to teach me more about this clue!

'what' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'beefeater renders?' is the wordplay.
'beefeater' becomes 'yeoman' (synonyms).
'renders?' becomes 'service' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'yeoman'+'service'='YEOMAN SERVICE'

'the' acts as a link.

Can you help me to learn more?

I've seen this clue in The Globe and Mail.

Want a hint initially instead of a full solution? Install my app