What mermaid has to swing from side to side? (8)
I believe the answer is:
fishtail
'what mermaid has' is the definition.
I can't tell whether this definition defines the answer.
'swing from side to side?' is the wordplay.
'swing from side' becomes 'fish' (I can't explain this - if you can you should give a lot more credence to this answer).
'to side?' becomes 'tail' (tail is a kind of side).
'fish'+'tail'='FISHTAIL'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for fishtail that I've seen before include "A skid from side to side" , "trailer may do" , "skid sideways" , "Merman's got one" , "swing the rear end" .)