Complaint from the French girl outside (7)
I believe the answer is:
malaria
'complaint' is the definition.
(malaria is a kind of disease)
'the french girl outside' is the wordplay.
'the french' becomes 'la' ('the' in French).
'girl' becomes 'maria' ().
'outside' means one lot of letters goes inside another.
'la' inserted inside 'maria' is 'MALARIA'.
'from' acts as a link.
(Other definitions for malaria that I've seen before include "Disease carried by mosquitoes" , "Mosquito-transmitted disease" , "Disease from bites by infected mosquitoes" , "Protozoal disease" , "Tropical disease" .)