What's this I see? Blast! A hole! (5)
I believe the answer is:
hello
'blast a hole' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe there's a link between them I don't understand?
'what's this i see?' is the wordplay.
'what's this i' becomes 'hel' (I can't justify this - if you can you should give a lot more credence to this answer).
'see?' becomes 'lo' ('lo' is an archaic exclamation meaning 'look!').
'hel'+'lo'='HELLO'
Can you help me to learn more?
(Other definitions for hello that I've seen before include "Expression of greeting" , "opener?" , "Surprised cry" , "Common greeting as on phone" , "royals dominate its pages?" .)