Has an ensign turned to monkey business? (11)
I believe the answer is:
shenanigans
'monkey business?' is the definition.
(I've seen this before)
'has an ensign turned' is the wordplay.
'turned' indicates an anagram.
'has'+'an'+'ensign'='hasanensign'
'hasanensign' is an anagram of 'SHENANIGANS'.
'to' acts as a link.
(Other definitions for shenanigans that I've seen before include "Monkey business" , "dirty work!" , "Mischief; dishonest activity" , "Mischievous trickery" .)