Ran out of gear - Bluth had been in front (5)
I believe the answer is:
idled
'ran out of gear' is the definition.
(an idling car is running but not in gear)
'bluth had been in front' is the wordplay.
'bluth had' becomes 'I'd' (where 'Bluth' is the setter of the crossword).
'been in front' becomes 'led' (to lead is to go in front).
'id'+'led'='IDLED'
(Other definitions for idled that I've seen before include "Of engine, just ticked over" , "Turned over" , "relaxed" , "Loitered" , "Spent time doing nothing" .)