Unhappy and confused client, so sad, accepts ring (12)
I believe the answer is:
disconsolate
'unhappy' is the definition.
(I've seen this before)
'confused client so sad accepts ring' is the wordplay.
'confused' indicates anagramming the letters.
'accepts' is an insertion indicator.
'ring' becomes 'o'.
'client'+'so'+'sad'='clientsosad'
'clientsosad' is an anagram of 'discnsolate'.
'discnsolate' placed around 'o' is 'DISCONSOLATE'.
'and' is the link.
(Other definitions for disconsolate that I've seen before include "Sad; beyond comfort" , "Unhappy and impossible to comfort" , "Dejected" , "Melancholy" , "Stuck with the blues" .)