Yank apprehends hard criminal (4)
I believe the answer is:
thug
'criminal' is the definition.
(thug is a kind of criminal)
'yank apprehends hard' is the wordplay.
'yank' becomes 'tug' (I've seen this before).
'apprehends' indicates putting letters inside.
'hard' becomes 'h'.
'tug' placed around 'h' is 'THUG'.
(Other definitions for thug that I've seen before include "16 21 [INDIAN IMPORT]" , "Hooligan" , "brute" , "Gangster" , "Brutal criminal" .)