With time, adopting working habit (4)
I believe the answer is:
wont
'habit' is the definition.
(I know that habit can be written as wont)
'with time adopting working' is the wordplay.
'with' becomes 'w' (abbreviation).
'time' becomes 't' (abbreviation).
'adopting' is an insertion indicator (inserted letters are taken on or adopted).
'working' becomes 'on' (on can mean working or activated).
'w'+'t'='wt'
'wt' placed around 'on' is 'WONT'.
(Other definitions for wont that I've seen before include "Habit" , "normal practice" , "Is not going to" , "customary behaviour" , "Succinct refusal" .)