What the beefeater renders? (6,7)
I believe the answer is:
'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).
'the' acts as a link.
Can you help me to learn more?