Start working with film crew, maybe ... (5)
I believe the answer is:
onset
'start' is the definition.
(both can mean the beginning of something)
'working with film crew maybe' is the wordplay.
'working' becomes 'on' (e.g. a machine is working or on).
'with' means one lot of letters go next to another.
'film crew maybe' becomes 'set' (I can't explain this - if you can you should give a lot more credence to this answer).
'on'+'set'='ONSET'
Can you help me to learn more?
(Other definitions for onset that I've seen before include "Start - opening moments" , "Beginning (of disease etc)" , "Beginning (of something often unpleasant)" , "Start - notes (anag)" , "Outbreak" .)