Recklessly, rather soon, Jack's accepted problematic gift (6,5)
I believe the answer is:
trojan horse
'accepted problematic gift' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'recklessly rather soon jack's' is the wordplay.
'recklessly' indicates anagramming the letters (I've seen this in other clues).
'jack' becomes 'J' (playing card abbreviation).
'rather'+'soon'+'j'='rathersoonj'
'rathersoonj' anagrammed gives 'TROJAN HORSE'.
Can you help me to learn more?
(Other definitions for trojan horse that I've seen before include "the Greeks aggressively piled out of" , "Iliad wooden construction" , "Subversive means of attack" , "Investment aid" , "admitted losing the war" .)