Bashful bird in red, possibly (6)
I believe the answer is:
demure
'bashful' is the definition.
(I've seen this in another clue)
'bird in red possibly' is the wordplay.
'bird' becomes 'emu' (emu is a type of bird).
'in' is an insertion indicator.
'possibly' indicates anagramming the letters.
'red' anagrammed gives 'dre'.
'emu' put inside 'dre' is 'DEMURE'.
(Other definitions for demure that I've seen before include "Pretending to be quiet and serious" , "Decorous; coy" , "Staid" , "Modest in manner" , "Reserved, modest, shy" .)