Last object — lion's share (7)
I believe the answer is:
endmost
'last' is the definition.
(similar in meaning)
'object lion's share' is the wordplay.
'object' becomes 'end' (I've seen this in other clues).
'lion's share' becomes 'most' (I've seen this in another clue).
'end'+'most'='ENDMOST'
(Other definitions for endmost that I've seen before include "Furthest away" , "Last in a row" , "Most distant" , "extreme situation" , "final" .)