Sense second conflict hasn't started (5)
I believe the answer is:
sight
'sense' is the definition.
(sight or vision is a sense)
'second conflict hasn't started' is the wordplay.
'second' becomes 's' (common abbreviation).
'conflict' becomes 'fight' (fight is a kind of conflict).
'hasn't started' means to remove the first letter.
'fight' with its initial letter taken off is 'ight'.
's'+'ight'='SIGHT'
(Other definitions for sight that I've seen before include "Vision, ability to see" , "Field of vision" , "Device used in aiming" , "Observe" , "Could be a jolly" .)