Acrobatic bird may turn upside-down (3)
I believe the answer is:
tit
'acrobatic bird' is the definition.
'tit' can be an answer for 'bird' (tit is a kind of bird). I'm not certain of the 'acrobatic' bit.
'turn upside-down' is the wordplay.
'turn' becomes 't' (abbreviation in Oxford Dictionary of Abbreviations).
'upside-down' becomes 'it' (I am not sure about this - if you are sure you should believe this answer much more).
't'+'it'='TIT'
'may' acts as a link.
Can you help me to learn more?
(Other definitions for tit that I've seen before include "18's [BIRD]" , "Small songbird" , "Small bird that lives off insects" , "What you swap for tat" , "Small garden bird" .)