Greek character missing a knack for sexiness (8)

'sexiness' is the definition.
Both the definition and answer are singular nouns.
Perhaps there's an association between them I don't understand?

'greek character missing a knack' is the wordplay.
I cannot quite see how this works, but
'character' could be 'nu' (nu is a kind of letter of the alphabet) and 'nu' is found in the answer.
This may be the basis of clue (or it may be nonsense).

'for' is the link.

Can you help me to learn more?