Amusing nobleman turning left (5)
I believe the answer is:
droll
'amusing' is the definition.
(I've seen this in another clue)
'nobleman turning left' is the wordplay.
'nobleman' becomes 'lord' (synonyms).
'turning' shows that the letters should be reversed in order.
'left' becomes 'l' (common abbreviation).
'lord' backwards is 'drol'.
'drol'+'l'='DROLL'
(Other definitions for droll that I've seen before include "Quaintly amusing" , "Funny" , "Comic" , "Mildly amusing" , "amusing, in a strange way" .)