Obsession of Arab, blocking title given to Lisa (9)
I believe the answer is:
monomania
'obsession' is the definition.
(I've seen this before)
'arab blocking title given to lisa' is the wordplay.
'arab' becomes 'Omani' (someone from Oman).
'blocking' means one lot of letters goes inside another (to block can mean to plug a gap in something).
'title given to lisa' becomes 'Mona' (as in the Mona Lisa).
'omani' put into 'mona' is 'MONOMANIA'.
'of' is the link.
(Other definitions for monomania that I've seen before include "Single-minded passion" , "obsessive single-mindedness" , "Unhealthy preoccupation with one thing" , "Obsession with one thing" .)