Insect ruined large sheet full of holes (7)
I believe the answer is:
stencil
'sheet full of holes' is the definition.
'insect ruined large' is the wordplay.
'ruined' indicates an anagram.
'large' becomes 'l'.
'insect' with letters rearranged gives 'stenci'.
'stenci'+'l'='STENCIL'
(Other definitions for stencil that I've seen before include "It helps get uniform print-out" , "Aid for drawing" , "Make patterns using thin perforated sheets" , "office plate" , "outline" .)