Dignitaries turned back on shyster (4)
I believe the answer is:
spiv
'shyster' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'dignitaries turned back' is the wordplay.
'dignitaries' becomes 'VIPs' ('VIP' can be a synonym of 'dignitary').
'turned back' is a reversal indicator.
'vips' reversed gives 'SPIV'.
'on' is the link.
Can you help me to learn more?
(Other definitions for spiv that I've seen before include "He's a flashy dresser who sells dodgy goods" , "Agreement" , "Person living off various dubious schemes" , "Flashy fellow who sells dodgy goods" , "Timepiece" .)