Officer is back, confusing mad liar (4,7)
I believe the answer is:
rear admiral
'officer' is the definition.
(I know that rear admiral is a type of officer)
'back confusing mad liar' is the wordplay.
'back' becomes 'rear' (something's rear is its back).
'confusing' indicates anagramming the letters.
'mad'+'liar'='madliar'
'madliar' is an anagram of 'admiral'.
'rear'+'admiral'='REAR-ADMIRAL'
'is' is the link.
(Other definitions for rear admiral that I've seen before include "Top brass" , "navy bigwig" , "Naval rank above commodore" , "Naval officer" .)