A low place; the centre of vice, though it's not obvious (7)
I believe the answer is:
cryptic
'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'.
'crypt'+'ic'='CRYPTIC'
'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" .)