Empty valise in French airport? That's too much! (6)

'too much' is the definition.
(I've seen this in another clue)

'empty valise in french airport?' is the wordplay.
'empty' means to remove the middle letters.
'in' indicates putting letters inside.
'french airport?' becomes 'orly' (I've seen this before).
'valise' with its centre removed is 've'.
've' put inside 'orly' is 'OVERLY'.

'that's' acts as a link.