Daughter in possession of coke truly suffering withdrawal symptoms (4,6)
I believe the answer is:
cold turkey
'withdrawal symptoms' is the definition.
(cold turkey is the process of drug withdrawal)
'daughter in possession of coke truly suffering' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'in possession of' means one lot of letters goes inside another.
'suffering' indicates an anagram.
'coke'+'truly'='coketruly'
'coketruly' with letters rearranged gives 'colturkey'.
'd' inserted within 'colturkey' is 'COLD TURKEY'.
(Other definitions for cold turkey that I've seen before include "(Symptoms of) sudden withdrawal of addictive drug" , "result of stopping drugs" , "When horse perhaps barred" , "Quick way to come off horse" , "Cure" .)