We will need security about source of messages here (7)

'here' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'we will need security about source of messages' is the wordplay.
'will need' means one lot of letters go next to another.
'security' becomes 'bail' (I've seen this in another clue).
'about' means one lot of letters goes inside another.
'source of' says to take the initial letters (the start - or source - of the word).
The first letter of 'messages' is 'm'.
'bail' going around 'm' is 'bmail'.
'we'+'bmail'='WEBMAIL'

Can you help me to learn more?