Here's my wash-up. I'm not sure there are any easy-ins to this puzzle, so it may prove a little more tricky than most (I'm a terrible judge of difficulty.)
ACROSS
1A. Embarrassing smell = BO + ship = SS. 4A. Insertion of salesman = REP into court = CT. 5A. Tamper with = RIG + papers = ID. 6A. Homophone of denial = NOT. DOWN 1D. Insertion of tuber = I into husky stuff = BRAN. 2D. Insertion of large = L into gob = SPIT. 3D. subtract last letter of research = STUDY. 4D. anag. RICK with nothing = O replacing me = I.