Considers bringing bird food over to cover first month (5)

'considers' is the definition.
(deeming is a kind of considering)

'bird food over to cover first month' is the wordplay.
'bird food' becomes 'seed' (I've seen this in another clue).
'over' says the letters should be written backwards.
'to cover' means one lot of letters goes inside another.
'first month' becomes 'm' (1st letter of 'month').
'seed' reversed gives 'dees'.
'dees' placed around 'm' is 'DEEMS'.

'bringing' acts as a link.