Bird flying to cave (6)
I believe the answer is:
avocet
'bird' is the definition.
(avocet is a kind of bird)
'flying to cave' is the wordplay.
'flying' indicates anagramming the letters.
'to'+'cave'='tocave'
'tocave' is an anagram of 'AVOCET'.
(Other definitions for avocet that I've seen before include "Shorebird - octave (anag)" , "Long-legged wader" , "Black-and-white shorebird with upward-curving bill" , "Might it sing" , "Wading bird with curved bill" .)