Disposition of person to wallow in pity (10)
I believe the answer is:
propensity
'disposition' is the definition.
(I know that propensity is a type of disposition)
'person to wallow in pity' is the wordplay.
'to wallow' is an anagram indicator.
'in' indicates putting letters inside.
'person' anagrammed gives 'ropens'.
'ropens' put inside 'pity' is 'PROPENSITY'.
'of' acts as a link.
(Other definitions for propensity that I've seen before include "Inclination; tendency" , "Bent" .)