A sub reportedly abandoned (5)
I believe the answer is:
alone
'abandoned' is the definition.
(I've seen this in another clue)
'a sub reportedly' is the wordplay.
'sub' becomes 'loan' (British term for advance against income).
'reportedly' shows a homophone (sound like).
'loan' is a homophone of 'lone'.
'a'+'lone'='ALONE'
(Other definitions for alone that I've seen before include "without another" , "Solo" , "Note of charges" , "Singly" , "Isolated from others" .)