Disease causing absence of French in Georgian city (5,5)
I believe the answer is:
black death
'disease' is the definition.
(Black Death is an example)
'absence of french in georgian city' is the wordplay.
'absence' becomes 'lack' (I've seen this in another clue).
'of french' becomes 'de' ('of' in French).
'in' means one lot of letters goes inside another.
'georgian city' becomes 'bath' (I've seen this before).
'lack'+'de'='lackde'
'lackde' inserted within 'bath' is 'BLACK DEATH'.
'causing' is the link.
(Other definitions for black death that I've seen before include "Disease" , "14th century plague" , "Fourteenth.-cent. plague" , "Great 14th-century killer epidemic" , "Bubonic plague epidemic" .)