It is hard to tell but I think that is a type 54 Republican overprint - "REP . IN-" over "DONESIA" within a frame. However most all the frame is missing except over inking at the top of the I which makes the N look somewhat like an R. I have several hundred Indonesia Interim stamps, including a dozen or so that are not in my album because the overprint is so unclear I can't tell what it is. This is borderline for whether I would put in in my album as a 54v-96 (the Dai Nippon classification - catalog value $1.20). It was very common for Republican overprints to be applied very faintly, or over inked and smudged, and everything in between. Not to mention that many of them were rather crude, even if applied correctly.