Bird single for second time (4)
I believe the answer is:
ibis
'bird' is the definition.
(ibis is a kind of bird)
'single for second time' is the wordplay.
'single' becomes 'I' (one).
'for' means one lot of letters go next to another.
'second time' becomes 'bis' (I've seen this before).
'i'+'bis'='IBIS'
(Other definitions for ibis that I've seen before include "sacred creature of Egypt" , "Wading bird with a down-curved bill" , "One has large bill" , "Flier" , "State of central US, capital Lincoln" .)