Sit back in obscure attics with data point (9)
I believe the answer is:
statistic
'data point' is the definition.
(statistic is a kind of data point)
'sit back in obscure attics' is the wordplay.
'back' is a reversal indicator.
'in' means one lot of letters goes inside another.
'obscure' is an anagram indicator.
'sit' in reverse letter order is 'tis'.
'attics' anagrammed gives 'static'.
'tis' going inside 'static' is 'STATISTIC'.
'with' is the link.
(Other definitions for statistic that I've seen before include "Data point" , "One single item of data" , "It could be vital" , "Piece of data" , "Collector's item" .)