Train engine's first to run about on time (9)
I believe the answer is:
entourage
'train' is the definition.
(thesaurus)
'engine's first to run about on time' is the wordplay.
'first' indicates taking the first letters.
'about' shows that the letters should be reversed in order.
'on' is an insertion indicator (as in clothing \'on\' a person).
'time' becomes 'age' (age is a kind of time**).
The first letter of 'engines' is 'e'.
'run' written backwards gives 'nur'.
'to' placed within 'nur' is 'ntour'.
'e'+'ntour'+'age'='ENTOURAGE'
(Other definitions for entourage that I've seen before include "Support team" , "Ego nature found in accompanying group" , "Supportive group" , "Group of attendants" , "The people accompanying a VIP" .)