Current cricketer finally breaking into Second Eleven (6)
I believe the answer is:
stream
'current' is the definition.
(synonyms)
'cricketer finally breaking into second eleven' is the wordplay.
'finally' says to take the final letters.
'breaking into' is an insertion indicator.
'second' becomes 's' (common abbreviation).
'eleven' becomes 'team' (eleven or XI can mean a football team).
The final letter of 'cricketer' is 'r'.
's'+'team'='steam'
'r' placed into 'steam' is 'STREAM'.
(Other definitions for stream that I've seen before include "Constant flow of liquid" , "Running liquid" , "Steady flow; pupil group" , "River - current" , "Quantity of water" .)