Rule a fund out -- investment ultimately crooked (10)
I believe the answer is:
fraudulent
'crooked' is the definition.
(thesaurus)
'rule a fund out investment ultimately' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'ultimately' indicates one should take the final letters.
The last letter of 'investment' is 't'.
'rule'+'a'+'fund'='ruleafund'
'ruleafund' with letters rearranged gives 'fraudulen'.
'fraudulen'+'t'='FRAUDULENT'
(Other definitions for fraudulent that I've seen before include "Intended to deceive" , "dishonest" .)