Sad jerk purchasing tabloid (6)
I believe the answer is:
tragic
'sad' is the definition.
(similar in meaning)
'jerk purchasing tabloid' is the wordplay.
'jerk' becomes 'tic' (I've seen this before).
'purchasing' means one lot of letters goes inside another (some letters take possession of others).
'tabloid' becomes 'rag' (informal term for a tabloid newspaper).
'tic' going around 'rag' is 'TRAGIC'.
(Other definitions for tragic that I've seen before include "Unfortunate" , "Awful" , "Extremely sad and distressing" , "Disastrous, appalling" , "heartbreaking" .)