Let Liberal rest (5)
I believe the answer is:
lease
'let' is the definition.
(as in to lease or let a building)
'liberal rest' is the wordplay.
'liberal' becomes 'l' (abbreviation).
'rest' becomes 'ease' (synonyms).
'l'+'ease'='LEASE'
(Other definitions for lease that I've seen before include "Contract for, say, use of building" , "Contract for use of land or building" , "From legal document" , "Let for money" , "Ghost" .)