A low place; the centre of vice, though it's not obvious (7)
I believe the answer is:
'it's not obvious' is the definition.
I can't judge whether this defines the answer.
'a low place the centre of vice' is the wordplay.
'a low place' becomes 'crypt' (crypt is a kind of place. I am not sure about the 'low' bit.).
'the centre of' means to look at the middle letters.
The centre of 'vice' is 'ic'.
'though' is the link.
Can you help me to learn more?
(Other definitions for cryptic that I've seen before include "The other kind of crossword" , "Hidden" , "Like our other puzzle" , "Type of crossword clue (but not this one!)" , "Enigmatic" .)