Grandmother keeping one recreational vehicle in paradise (7)
I believe the answer is:
nirvana
'paradise' is the definition.
(synonyms)
'grandmother keeping one recreational vehicle' is the wordplay.
'grandmother' becomes 'nana' (I've seen this before).
'keeping' indicates putting letters inside.
'one' becomes 'I' (Roman numeral).
'recreational vehicle' becomes 'RV' (abbreviation).
'i'+'rv'='irv'
'nana' enclosing 'irv' is 'NIRVANA'.
'in' is the link.
(Other definitions for nirvana that I've seen before include "Buddhist version of Paradise" , "Transcendent state - US grunge band" , "Buddhist paradise or hereafter" , "Transcendent state of Buddhists" , "US rock band" .)