Traders ultimately falter and suffer, shown in terse broadcast (9)
I believe the answer is:
retailers
'traders' is the definition.
(I've seen this before)
'ultimately falter and suffer shown in terse broadcast' is the wordplay.
'ultimately' suggests the final letters.
'and' says to put letters next to each other.
'suffer' becomes 'ail' (ailing is a kind of suffering**).
'shown in' indicates putting letters inside.
'broadcast' indicates anagramming the letters.
The last letter of 'falter' is 'r'.
'terse' anagrammed gives 'eters'.
'ail' inserted into 'eters' is 'etailers'.
'r'+'etailers'='RETAILERS'
(Other definitions for retailers that I've seen before include "Sellers" , "They sell to the public" , "traders" , "shopkeepers" .)