Allowance for rent, missing the last share (10)
I believe the answer is:
toleration
'allowance' is the definition.
(thesaurus)
'for rent missing the last share' is the wordplay.
'for rent' becomes 'to let' (I've seen this before).
'missing the last' means to remove the last letter.
'share' becomes 'ration' (a ration is a share of a limited resource).
'tolet' with its last letter removed is 'tole'.
'tole'+'ration'='TOLERATION'
(Other definitions for toleration that I've seen before include "Indulgence" , "Forbearance" , "liberalism" , "Allowance of what is not approved" , "liberality" .)