Delinquent's heartless, loafing around below house (8)
I believe the answer is:
hooligan
'delinquent's' is the definition.
(thesaurus)
'heartless loafing around below house' is the wordplay.
'heartless' means to remove the middle letters.
'around' is an anagram indicator.
'below' is a charade indicator (letters next to each other) (in a down clue, some letters go below others).
'house' becomes 'ho' (abbreviation for house).
'loafing' with its centre removed is 'loaing'.
'loaing' anagrammed gives 'oligan'.
'oligan' after 'ho' is 'HOOLIGAN'.
(Other definitions for hooligan that I've seen before include "Ruffian, noisy troublemaker" , "Tough" , "Violent lout" , "Rowdy yob" , "A young ruffian" .)