Honour terms of previous invoice with large corporation? (5)
I believe the answer is:
obese
'with large corporation?' is the definition.
(corporation can humorously mean body fat)
'honour terms of previous invoice' is the wordplay.
'honour' becomes 'obe' (Order of the British Empire).
'terms of' says to take the final letters (term can mean the end of something).
The last letters of 'previous invoice' are 'se'.
'obe'+'se'='OBESE'
(Other definitions for obese that I've seen before include "getting well-upholstered" , "Dangerously corpulent" , "Morbidly overweight" , "Extremely overweight" , "Huge" .)