Old man hacks into renowned computer (7)
I believe the answer is:
notepad
'computer' is the definition.
(I've seen this before)
'old man hacks into renowned' is the wordplay.
'old man hacks' becomes 'pa' (I can't justify this - if you can you should believe this answer much more).
'into' means one lot of letters goes inside another.
'renowned' becomes 'noted' (synonyms).
'pa' put inside 'noted' is 'NOTEPAD'.
Can you help me to learn more?
(Other definitions for notepad that I've seen before include "writer's block" , "Block writer might have" , "type of computer" , "Where memos get written" , "Pocket-sized computer" .)