Vehicle's run times troubled conservationists (10)
I believe the answer is:
instrument
'vehicle's' is the definition.
(thesaurus)
'run times troubled conservationists' is the wordplay.
'troubled' indicates an anagram.
'conservationists' becomes 'nt' (abbreviation for National Trust).
'run'+'times'='runtimes'
'runtimes' with letters rearranged gives 'instrume'.
'instrume'+'nt'='INSTRUMENT'
(Other definitions for instrument that I've seen before include "Means of precision work (or music-making)" , "legal document" , "power" , "Joanna, perhaps" , "Word puzzle" .)