Swing round as the Welsh start a comeback (4)
I believe the answer is:
slew
'swing round' is the definition.
'slew' can be an answer for 'swing' (both can mean to slide out of control). I'm not sure about the 'round' bit.
'the welsh start a comeback' is the wordplay.
'start' means to remove the last letter (I've seen 'starts' mean this).
'a comeback' shows that the letters should be reversed in order.
'welsh' with its last letter taken off is 'wels'.
'wels' reversed gives 'SLEW'.
'as' is the link.
Can you help me to learn more?
(Other definitions for slew that I've seen before include "a great number in Chicago" , "Dispatched" , "Greatly amused" , "murdered" , "twisted position" .)