Really big cobblers - even the last one (5)
I believe the answer is:
obese
'really big' is the definition.
(I've seen this in another clue)
'cobblers even the last one' is the wordplay.
'even' indicates alternate letters (even-numbered letters are used).
'the last' says to take the final letters (I've seen 'the last of' mean this).
The last letter of 'one' is 'e'.
The alternating letters of 'cobblers' are 'obes'.
'obes'+'e'='OBESE'
(Other definitions for obese that I've seen before include "round" , "Extremely overweight" , "carrying remarkable weight" , "Unusually fat" , "with a pot?" .)