Garden bird nibbled morsel (6)
I believe the answer is:
titbit
'morsel' is the definition.
(I've seen this before)
'garden bird nibbled' is the wordplay.
I cannot quite see how this works, but
'bird' could be 'tit' (tit is a kind of bird) and 'tit' is found in the answer.
'nibbled' could be 'bit' (to nibble is to take a small bite) and 'bit' is found within the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for titbit that I've seen before include "Choice piece, food or gossip" , "Choice bit of something, food or gossip" , "Dainty morsel" , "Small item of gossip" , "choice morsel" .)