Maybe real cool to cover up a congenital defect (7)
I believe the answer is:
harelip
'a congenital defect' is the definition.
'harelip' can be an answer for 'defect' (I have seen 'Facial defect' mean 'harelip' so perhaps 'defect' could also mean 'harelip'). I am not certain of the 'a congenital' bit.
'maybe real cool to cover up' is the wordplay.
'maybe' indicates an anagram.
'cool' becomes 'hip'.
'to cover up' means one lot of letters goes inside another.
'real' with letters rearranged gives 'arel'.
'arel' going inside 'hip' is 'HARELIP'.
Can you help me to learn more?
(Other definitions for harelip that I've seen before include "congenital split" , "Congenital mouth defect" , "Facial defect" , "Facial disfigurement" .)