Impressed? Not me! Rubbish web designers (7)
I believe the answer is:
spiders
'web designers' is the definition.
(creatures who make webs)
'impressed? not me rubbish' is the wordplay.
'not' suggests deleting specific letters.
'rubbish' indicates anagramming the letters (a poor quality or rubbish spelling of the letters).
'impressed' with 'me' taken out is 'iprssed'.
'iprssed' with letters rearranged gives 'SPIDERS'.
(Other definitions for spiders that I've seen before include "Web weavers" , "Arachnids" , "Predators on the web" , "Insects; rests" , "14 [BOWIE] 's band from 26 [MARS]" .)