Racer bickers about content that's pretty harsh (7)
I believe the answer is:
acerbic
'pretty harsh' is the definition.
'acerbic' can be an answer for 'harsh' (I've seen this in another clue). I am not certain of the 'pretty' bit.
'racer bickers about content' is the wordplay.
'content' says the answer is hidden in the clue (letters contained within the clue).
'ACERBIC' is hidden in the letters of 'racer bickers about'.
'that's' is the link.
Can you help me to learn more?
(Other definitions for acerbic that I've seen before include "tart" , "Bitter-tasting" , "Sharp, forthright" , "Tasting sour or caustic in speech" , "Sour; sharp" .)