Tear a strip off favourite underlay of jalopy (6)
I believe the answer is:
carpet
'tear a strip off' is the definition.
(both can mean to severely criticise)
'favourite underlay of jalopy' is the wordplay.
I cannot really understand how this works, but
'favourite' could be 'pet' (synonyms) and 'pet' is found within the answer.
'jalopy' could be 'car' (I've seen this in another clue) and 'car' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for carpet that I've seen before include "has pull up sharply" , "On the ......- getting a ticking-off" , "from Brussels, for instance" , "Dress down" , "Slate" .)