Final release of vehicle trapped in blustery rain (7)
I believe the answer is:
nirvana
'final release' is the definition.
(transcendent state which is the goal in Buddhism)
'vehicle trapped in blustery rain' is the wordplay.
'vehicle' becomes 'van' (van is a kind of vehicle).
'trapped in' is an insertion indicator.
'blustery' indicates anagramming the letters.
'rain' is an anagram of 'nira'.
'van' placed within 'nira' is 'NIRVANA'.
'of' acts as a link.
(Other definitions for nirvana that I've seen before include "Eastern place or state of bliss" , "Hindu or Buddhist blissful meditative state" , "religious ecstasy" , "US rock band" , "Tranquillity" .)