Report of solitary advance (4)
I believe the answer is:
loan
'advance' is the definition.
(an advance is a loan)
'report of solitary' is the wordplay.
'report of' indicates a 'sounds like' (homophone) clue (how it'd sound if reported).
'solitary' becomes 'lone' (synonyms).
'lone' sounds like 'LOAN'.
(Other definitions for loan that I've seen before include "Money borrowed; lend" , "Mortgage" , "One acquired temporarily" , "Cash advance" , "Something borrowed" .)