Share place on a lake (10)
I believe the answer is:
allocation
'share' is the definition.
(allocation is a kind of share)
'place on a lake' is the wordplay.
'place' becomes 'location' (I've seen this before).
'on' means one lot of letters go next to another.
'lake' becomes 'L' (geographical abbreviation).
'a'+'l'='al'
'location' put after 'al' is 'ALLOCATION'.
(Other definitions for allocation that I've seen before include "Share" , "budget" , "Allotment" , "Distribution, assignment" , "Apportionment" .)