Crazy being caught inside lavatory (4)
I believe the answer is:
loco
'crazy' is the definition.
(thesaurus)
'caught inside lavatory' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'inside' means one lot of letters goes inside another.
'lavatory' becomes 'loo' (loo is a kind of lavatory).
'c' put inside 'loo' is 'LOCO'.
'being' is the link.
(Other definitions for loco that I've seen before include "Potty" , "Mad - train" , "Barmy (Spanish) - engine (abbr)" , "Crazy in America - cool, man" , "Round the bend" .)