Fit French aunt didn't finish drink (7)
I believe the answer is:
tantrum
'fit' is the definition.
('tantrum' can be a synonym of 'fit')
'french aunt didn't finish drink' is the wordplay.
'french aunt' becomes 'tan' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'finish' indicates one should take the final letters.
'drink' becomes 'rum' (rum is a kind of drink).
The last letter of 'didnt' is 't'.
'tan'+'t'+'rum'='TANTRUM'
Can you help me to learn more?
(Other definitions for tantrum that I've seen before include "Display of bad temper" , "Hissy fit" , "Pet, temper" , "Spoilt brat's fit" , "Childish angry outburst" .)