Question

Then sleek as a lizard and alert and abrupt the line from laburnum top which poetic decide is used in it

Answer 1

Answer:

its Personification

because here poet is comparing the lizards characteristics with the goldfinch

Answer 2

Simile and visual imagery are the figurative devices used in the line.

EXPLANATION:  

In the poem Laburnum Top, Ted Hughes very dexterously paints the picture of the Laburnum Tree Top where resides many animals. The tree top is usually quiet and serene until intruded by a bird family residing in it.

To portray its quietness and the stealthy arrival of the gold Finch to its nest the poet uses the simile of the stealthy lizard. The lizard is a very alert and abrupt creature always watchful. The bird too is very observant and careful lest it be caught by some onlooker as it comes to feed its hungry nestlings. By the simile the poet creates a visual imagery of the scene.