Left omen around - that's sharp (5)
I believe the answer is:
lemon
'sharp' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'left omen around' is the wordplay.
'left' becomes 'l' (common abbreviation).
'around' is an anagram indicator.
'omen' with letters rearranged gives 'emon'.
'l'+'emon'='LEMON'
'that's' is the link.
Can you help me to learn more?
(Other definitions for lemon that I've seen before include "Shade of yellow - fruit" , "Yellow fruit (it's also the answer!)" , "Fruit squeezed on Pancake Day?" , "something defective" , "Fruit (which is proverbially "the answer")" .)