Staff in charge? That's a bit crazy (5)
I believe the answer is:
manic
'bit crazy' is the definition.
'manic' can be an answer for 'crazy' (I've seen this before). I'm not certain of the 'bit' bit.
'staff in charge?' is the wordplay.
'staff' becomes 'man' (as in staffing or manning a particular place).
'in charge?' becomes 'ic' (abbreviation for 'in charge').
'man'+'ic'='MANIC'
'that's a' acts as a link.
Can you help me to learn more?
(Other definitions for manic that I've seen before include "Unnaturally excited" , "Of mental state veering from depression to excitement" , "Berserk" , "Wildly excited" , "Pathologically excited" .)