Twins wrong to take drugs to one appearing in court (7)
I believe the answer is:
witness
'one appearing in court' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'twins wrong to take drugs' is the wordplay.
'wrong' indicates anagramming the letters.
'to take' means one lot of letters goes inside another.
'drugs' becomes 'es' (E is a term for an ecstasy pill).
'twins' is an anagram of 'witns'.
'witns' enclosing 'es' is 'WITNESS'.
'to' is the link.
Can you help me to learn more?
(Other definitions for witness that I've seen before include "Evidence, proof" , "It's news (anag.)" , "One giving evidence" , "Court testifier" , "Spectator" .)