Was leader by editor on the left? (3)
I believe the answer is:
led
'was leader' is the definition.
(a leader leads people)
'editor on the left?' is the wordplay.
'editor' becomes 'ed' (abbreviation).
'on' is a charade indicator (letters next to each other).
'the left?' becomes 'l' (common abbreviation).
'ed' put after 'l' is 'LED'.
'by' acts as a link.
(Other definitions for led that I've seen before include "associated with Zeppelin" , "Was guiding" , "Went ahead" , "was in the van" , "Took by the hand and showed the way" .)