Ruling again repeatedly in first gear (7)

I believe the answer is:

reining

'ruling' is the definition.
('rein' can be a synonym of 'rule')

'again repeatedly in first gear' is the wordplay.
'repeatedly in' means two substitutions for 'in'.
'again' becomes 're' (prefix meaning 'again').
'first gear' becomes 'g' (1st letter of 'gear').
're'+'in'+'in'+'g'='REINING'

I've seen this clue in the Sydney Morning Herald.

Want a hint initially instead of a full solution? Install my app