Diplomat confounded mathematicians disregarding animism (7)
I believe the answer is:
attache
'diplomat' is the definition.
(I've seen this before)
'confounded mathematicians disregarding animism' is the wordplay.
'confounded' indicates anagramming the letters.
'disregarding' suggests deleting specific letters.
'mathematicians' with 'animism' taken out is 'theatca'.
'theatca' is an anagram of 'ATTACHE'.
(Other definitions for attache that I've seen before include "Embassy worker" , "This case is for carrying documents" , "That ace (anag.)" , "Small rectangular document case" , "This small rectangular case carries documents" .)