Having a lot to lose? (5)
I believe the answer is:
obese
'having a lot to lose?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for obese that I've seen before include "Extremely overweight" , "Grossly fat" , "likely to tip the balance?" , "Very substantial" , "Falstaffian" .)