Fit one in late bus that's been diverted (8)
I believe the answer is:
suitable
'fit' is the definition.
(similar in meaning)
'one in late bus that's been diverted' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in' indicates putting letters inside.
'that's been diverted' indicates an anagram (letters must be diverted to different positions).
'late'+'bus'='latebus'
'latebus' anagrammed gives 'sutable'.
'i' placed inside 'sutable' is 'SUITABLE'.
(Other definitions for suitable that I've seen before include "Fitting, apt" , "Appropriate, apt" , "qualified" , "Convenient" , "In keeping" .)