Small warbler (4)
I believe the answer is:
wren
'small warbler' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for wren that I've seen before include "17th Century architect" , "held up by wings at small scale?" , "Type of small bird" , "Tiny brown songbird with short erect tail" , "Small singer" .)