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' means one lot of letters goes inside another.
'that's been diverted' is an anagram indicator (letters must be diverted to different positions).
'late'+'bus'='latebus'
'latebus' anagrammed gives 'sutable'.
'i' going within 'sutable' is 'SUITABLE'.
(Other definitions for suitable that I've seen before include "Fitting, apt" , "Appropriate, apt" , "qualified" , "Convenient" , "In keeping" .)