Landing ground needs helium for large computer (7)
I believe the answer is:
helipad
'landing ground' is the definition.
The definition suggests a singular noun which matches the answer.
'helium for large computer' is the wordplay.
'helium' becomes 'he' (chemical symbol).
'for' means one lot of letters go next to another.
'large' becomes 'l'.
'computer' becomes 'ipad' (I can't justify this - if you can you should believe this answer much more).
'he'+'l'+'ipad'='HELIPAD'
'needs' acts as a link.
Can you help me to learn more?
(Other definitions for helipad that I've seen before include "Landing area for copters" , "chopper came down" , "Area for choppers to take off and land" , "Vertical take-off and landing area" , "Area for wingless aircraft to take off and land" .)