Free love enclosure (4)
I believe the answer is:
open
'free' is the definition.
('open' can be similar in meaning to 'free')
'love enclosure' is the wordplay.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'enclosure' becomes 'pen' (pen is a kind of enclosure).
'o'+'pen'='OPEN'
(Other definitions for open that I've seen before include "Undecided" , "Not closed or obstructed" , "Public" , "gaping" , "simple" .)