### Clue: Bird found mostly in the same place (4)
### Answer: IBIS 
 ### Explanation: Definition: Bird
 **3 out of 4 letters of**(mostly) "ibid."(abbrev. for "ibidem";in the same place, used to refer to the same book, chapter, etc. cited just before). The wordplay for "s" seems to be missing? I thought of "ib."(alternative to "ibid.") + "is"(found in), but then, "mostly" would be incorrect.