Realise and convey how to act as a servant (5,3,5)
I believe the answer is:
fetch and carry
'to act as a servant' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'realise and convey' is the wordplay.
'realise' becomes 'fetch' (I can't explain this - if you can you should believe this answer much more).
'convey' becomes 'carry' (carrying is a kind of conveying).
'fetch'+'and'+'carry'='FETCH AND CARRY'
'how' is the link.
Can you help me to learn more?
(Other definitions for fetch and carry that I've seen before include "Perform humble services for someone - rather fancy CD (anag)" , "Perform menial tasks" .)