Has been returning saw (3)
I believe the answer is:
was
'has been' is the definition.
(I've seen this in another clue)
'returning saw' is the wordplay.
'returning' is a reversal indicator.
'saw' reversed gives 'WAS'.
(Other definitions for was that I've seen before include "'Is, in the past (3)'" , "Is no longer" , "(I/he) existed" , "Existed in the past" , "Used to be" .)