Enjoy being insane very much (4,5)
I believe the answer is:
like crazy
'very much' is the definition.
(I've seen this before)
'enjoy being insane' is the wordplay.
'enjoy' becomes 'like' (like can mean to appreciate or enjoy something).
'being insane' becomes 'crazy' ('crazy' can be similar in meaning to 'insane').
'like'+'crazy'='LIKE CRAZY'
(Other definitions for like crazy that I've seen before include "great enthusiasm" , "Very much" , "Furiously" .)