Large storage site close to telephone network (7)
I believe the answer is:
lattice
'network' is the definition.
(I've seen this before)
'large storage site close to telephone' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'storage site' becomes 'attic' (I've seen this in another clue).
'close to' indicates one should take the final letters (the close of something is the end).
The final letter of 'telephone' is 'e'.
'l'+'attic'+'e'='LATTICE'
(Other definitions for lattice that I've seen before include "Structure with criss-cross strips" , "Openwork structure" , "Regular atomic structure" , "Sort of window" , "Framework of crossed bars as in windows" .)