Chap in charge is deranged (5)
I believe the answer is:
manic
'is deranged' is the definition.
(I've seen this before)
'chap in charge' is the wordplay.
'chap' becomes 'man' (chap can mean a man).
'in charge' becomes 'ic' (abbreviation for 'in charge').
'man'+'ic'='MANIC'
(Other definitions for manic that I've seen before include "Showing wild energy" , "Ludicrously busy" , "Very energetic - crazed" , "Unnaturally excited" , "Hectic" .)