Hackneyed Italian number, railing away (10)
I believe the answer is:
unoriginal
'hackneyed' is the definition.
(similar in meaning)
'italian number railing away' is the wordplay.
'italian number' becomes 'u-no' (I've seen this in another clue).
'away' is an anagram indicator (letters move away from their original places).
'railing' anagrammed gives 'riginal'.
'uno'+'riginal'='UNORIGINAL'
(Other definitions for unoriginal that I've seen before include "stock" , "lacking novelty" , "second-hand" , "poorly copied" .)