Stagehand picked up flu, getting critical (3,4)
I believe the answer is:
'stagehand' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.
'picked up flu getting critical' is the wordplay.
'picked up' shows a homophone (sound like).
'flu' becomes 'grippe' (synonyms).
'getting' is a charade indicator (letters next to each other).
'critical' becomes 'key' (I've seen this in other clues).
'grippe' sounds like 'grip'.
'grip' after 'key' is 'KEY GRIP'.
Can you help me to learn more?
(Another definition for key grip that I've seen is " film-set supervisor".)