British articles on arsenic are crazy (7)
I believe the answer is:
bananas
'are crazy' is the definition.
(thesaurus)
'british articles on arsenic' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in BBC).
'articles' becomes 'anan' (the indefinite article 'an', twice).
'on' means one lot of letters go next to another.
'arsenic' becomes 'As' (As is the chemical symbol for arsenic).
'b'+'anan'+'as'='BANANAS'
(Other definitions for bananas that I've seen before include "Fruit - nuts" , "Mad - curved fruits" , "hands" , "off 27 [TROLLEY]" , "Fruit; mad" .)