It hurts to block extremely short pass (7)
I believe the answer is:
voucher
'pass' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'it hurts to block extremely short' is the wordplay.
'it hurts' becomes 'ouch' (both might be said when in pain).
'to block' indicates putting letters inside (block can mean to fill a hole in something).
'extremely short' becomes 'ver' (I've seen this in other clues).
'ouch' inserted within 'ver' is 'VOUCHER'.
Can you help me to learn more?
(Other definitions for voucher that I've seen before include "Document that can be exchanged for goods" , "Something that can be exchanged for goods or services" , "Ticket" , "Paper token" , "Document that serves as evidence of some expenditure" .)