Bird by altar sobs uncontrollably (9)
I believe the answer is:
albatross
'bird' is the definition.
(albatross is a kind of bird)
'by altar sobs uncontrollably' is the wordplay.
'by' means one lot of letters go next to another.
'uncontrollably' indicates an anagram (I've seen this in other clues).
'altar' after 'sobs' is 'sobsaltar'.
'sobsaltar' is an anagram of 'ALBATROSS'.
(Other definitions for albatross that I've seen before include "Great hole" , "Very good score" , "See 7" , "Long-winged sea-bird, a constant burden" , "Ocean bird; a burden (round neck)" .)