Crash of lone bus involving middle of bus? It's unclear (8)
I believe the answer is:
nebulous
'unclear' is the definition.
(thesaurus)
'crash of lone bus involving middle of bus?' is the wordplay.
'crash of' indicates anagramming the letters (I've seen this in other clues).
'involving' indicates putting letters inside.
'middle of' indicates the central letters.
The central letter of 'bus' is 'u'.
'lone'+'bus'='lonebus'
'lonebus' with letters rearranged gives 'neblous'.
'neblous' going around 'u' is 'NEBULOUS'.
'it's' acts as a link.
(Other definitions for nebulous that I've seen before include "Cloudy and vague" , "Vague, lacking a distinct shape" , "Vague and formless" , "Indistinct and vague" , "'Cloudy, lacking definite form (8)'" .)