Crow by last month on verge of extinction (5)
I believe the answer is:
exult
'crow' is the definition.
(I've seen this before)
'by last month on verge of extinction' is the wordplay.
'by' becomes 'x' (2 by 4 is 2 x 4).
'last month' becomes 'ult' (short for 'last month' in correspondence).
'on' says to put letters next to each other.
'verge of' indicates taking the first letters.
The initial letter of 'extinction' is 'e'.
'x'+'ult'='xult'
'xult' after 'e' is 'EXULT'.
(Other definitions for exult that I've seen before include "Feel or express triumph" , "Rejoice exceedingly, glory in (5)" , "Feel triumphantly elated" , "Be euphoric" , "Express great joy" .)