The sign of The French Duck? (3)
I believe the answer is:
leo
'the sign' is the definition.
(star sign)
'the french duck?' is the wordplay.
'the french' becomes 'le' ('the' in French).
'duck?' becomes 'o' (resembles zero - 'duck' in cricket).
'le'+'o'='LEO'
'of' acts as a link.
(Other definitions for leo that I've seen before include "house" , "certain stars" , "Singer-songwriter Sayer, b. 1949" , "A constellation; several popes" , "born in July or August" .)