Fitting carpet that’s oddly defective (3)
'fitting' is the definition.
(both mean appropriate)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for apt that I've seen before include "Appropriate for Pat" , "Tap (anag.)" , "Liable" , "Inclined; appropriate" , "Prone" .)
'fitting' is the definition.
(thesaurus)
'carpet that's oddly defective' is the wordplay.
'that's oddly' indicates alternate letters (letters in the odd-numbered positions are used).
'defective' is an anagram indicator.
The alternate letters of 'carpet' are 'apt'.
'apt' is an anagram of 'PAT'.
(Other definitions for pat that I've seen before include "Affectionate gesture - postman" , "well-rehearsed" , "Apt for tender touch" , "'Light touch, on the back say (3)'" , "Some butter, maybe" .)