It's mad, mad, in 'The Thick of It' (6)
I believe the answer is:
amidst
'the thick of it' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'it's mad mad' is the wordplay.
'mad' indicates anagramming the letters.
'its'+'mad'='itsmad'
'itsmad' is an anagram of 'AMIDST'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for amidst that I've seen before include "In the thick of" , "Surrounded by" , "Embraced by" , "Beset" , "It's mad (anag.)" .)