Bewilderment about manoeuvring of unions (9)
I believe the answer is:
confusion
'bewilderment' is the definition.
(thesaurus)
'about manoeuvring of unions' is the wordplay.
'about' becomes 'c' (abbreviation for circa).
'manoeuvring' indicates anagramming the letters.
'of'+'unions'='ofunions'
'ofunions' with letters rearranged gives 'onfusion'.
'c'+'onfusion'='CONFUSION'
(Other definitions for confusion that I've seen before include "Discombobulation, disarray" , "Perplexity" , "Bewilderment - disorder" , "Uncertainty" , "Chaos" .)