People who, having turned in, dash out! (6)
I believe the answer is:
danish
'people who' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'turned in dash out' is the wordplay.
'turned' shows that the letters should be reversed in order.
'out' indicates putting letters inside.
'in' in reverse letter order is 'ni'.
'ni' put inside 'dash' is 'DANISH'.
'having' is the link.
Can you help me to learn more?
(Other definitions for danish that I've seen before include "Hamlet's nationality" , "Pastry, from Copenhagen say" , "European language" , "Like Hans Andersen" , "Hamlet was and bacon may be" .)