Succeeding by breaking clear (4)
I believe the answer is:
next
'succeeding' is the definition.
('next' can be similar in meaning to 'succeeding')
'by breaking clear' is the wordplay.
'by' becomes 'x' (multiplication sign).
'breaking' indicates putting letters inside.
'clear' becomes 'net' (as in net profit).
'x' inserted within 'net' is 'NEXT'.
(Other definitions for next that I've seen before include "First in line" , "The one following or adjacent" , "Proximate" , "Retailer" , "Coming nearest in order - come, please!" .)