Prison is more funky! (6)
I believe the answer is:
cooler
I believe this clue is a double definition.
'prison' is the first definition.
(informal term for a prison)
'more funky' is the second definition.
'is' acts as a link.
(Other definitions for cooler that I've seen before include "Prison - less warm" , "Nick" , "Fan" , "It's not so hot" , "less enthusiastic" .)