Start working and make crosswords (5)
I believe the answer is:
onset
'start' is the definition.
(both can mean the beginning of something)
'working and make crosswords' is the wordplay.
'working' becomes 'on' (on can mean working or activated).
'and' is a charade indicator (letters next to each other).
'make crosswords' becomes 'set' (I am not sure about this - if you are sure you should believe this answer much more).
'on'+'set'='ONSET'
Can you help me to learn more?
(Other definitions for onset that I've seen before include "Kick-off" , "Start - attack" , "Advent" , "Storming" , "First signs" .)