Most inexpensive carpet hid profligacy (4,5)

I believe the answer is:

dirt cheap

I'm a little stuck... Click here to teach me more about this clue!

'most' is the definition.
Both the answer and definition are adjectives. Perhaps they are linked in a way I don't understand?

'inexpensive carpet hid profligacy' is the wordplay.
'carpet hid' can be anagrammed to 'DIRT-CHEAP'.
However, I'm not clear how this is indicated.

Can you help me to learn more?

(Other definitions for dirt cheap that I've seen before include "Going for a song" , "Extremely inexpensive" , "rock-bottom prices" , "attractive to potential buyer?" , "Ridiculously inexpensive" .)

I've seen this clue in the Sydney Morning Herald.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.