Roonerspism (10)
I believe the answer is:
spoonerism
I'm afraid I can't explain this answer.
Can you help me to learn more?
(Other definitions for spoonerism that I've seen before include "Verbal exchange of leading characters" , ""A lopping of sweaters", for example" , "occasional cluing technique" , "A slip of the tongue? -- no promises (anag)" , "Burly chassis for Shirley Bassey, say?" .)