Yank coming across hard and tough (4)
I believe the answer is:
thug
'tough' is the definition.
(both can mean a violent person)
'yank coming across hard' is the wordplay.
'yank' becomes 'tug' (both can mean to pull sharply).
'coming across' means one lot of letters goes inside another.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'tug' going around 'h' is 'THUG'.
'and' acts as a link.
(Other definitions for thug that I've seen before include "Gorilla" , "Heavy" , "Violent hoodlum" , "Burrowing crustacean" , "Hood" .)