Before new merger, business in a muddle (9)
I believe the answer is:
confusion
'a muddle' is the definition.
(thesaurus)
'before new merger business' is the wordplay.
'before' says to put letters next to each other.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'merger' becomes 'fusion' (synonyms).
'business' becomes 'co' (short for company).
'n'+'fusion'='nfusion'
'nfusion' put after 'co' is 'CONFUSION'.
'in' acts as a link.
(Other definitions for confusion that I've seen before include "Uncertainty" , "Discombobulation, disarray" , "Chaos" , "Perplexity" , "Shame!" .)