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' (both can mean a goal or purpose).
'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" .)