Sleep around, having accepted liberal proposal (4)
I believe the answer is:
plan
'proposal' is the definition.
(a proposal is a plan of action)
'sleep around having accepted liberal' is the wordplay.
'sleep' becomes 'nap' (a nap is a short sleep).
'around' says the letters should be written in reverse.
'having accepted' is an insertion indicator (inserted letters are accepted or received).
'liberal' becomes 'l' (abbreviation).
'nap' in reverse letter order is 'pan'.
'pan' placed around 'l' is 'PLAN'.
(Other definitions for plan that I've seen before include "Agenda" , "Detailed proposal" , "Formulate" , "Aim" , "Scheme to achieve something" .)