Loathe delinquent holding group back (6)
I believe the answer is:
detest
'loathe' is the definition.
(I've seen this before)
'delinquent holding group back' is the wordplay.
'delinquent' becomes 'ted' (I've seen this in other clues).
'holding' means one lot of letters goes inside another.
'group' becomes 'set' (both can mean a collection).
'back' is a reversal indicator.
'ted' enclosing 'set' is 'tseted'.
'tseted' backwards is 'DETEST'.
(Other definitions for detest that I've seen before include "Dislike heartily" , "Greatly hate" , "Cordially laothe" , "Cordially dislike and loathe" , "Find repulsive" .)