Roman observers primarily unhappy with the Italian transport system (8)
I believe the answer is:
monorail
'transport system' is the definition.
(I've seen this before)
'roman observers primarily unhappy with the italian' is the wordplay.
'primarily' suggests taking the first letters.
'unhappy' indicates anagramming the letters.
'with' is a charade indicator (letters next to each other).
'the italian' becomes 'il' (the in Italian).
The initial letter of 'observers' is 'o'.
'roman'+'o'='romano'
'romano' is an anagram of 'monora'.
'monora'+'il'='MONORAIL'
(Other definitions for monorail that I've seen before include "train" , "Suspended railway" , "Hanging transport system" , "Type of railway" , "Form of transport" .)