Obsession having wrong info about cab back (8)
I believe the answer is:
fixation
'obsession' is the definition.
(I know that obsession can be written as fixation)
'wrong info about cab back' is the wordplay.
'wrong' indicates an anagram.
'about' means one lot of letters goes inside another.
'cab' becomes 'taxi' (taxi cab).
'back' shows that the letters should be reversed in order.
'taxi' in reverse letter order is 'ixat'.
'info' is an anagram of 'fion'.
'fion' going around 'ixat' is 'FIXATION'.
'having' is the link.
(Other definitions for fixation that I've seen before include "thing" , "Unhealthy preoccupation" , "Obsession" , "Obsessive interest" .)