Special signal, something my old man may use in battle? (8)
I believe the answer is:
password
'something my old man may use in battle?' is the definition.
I can't tell whether this definition defines the answer.
'special signal' is the wordplay.
'special' becomes 'pass' (I can't justify this - if you can you should believe this answer much more).
'signal' becomes 'word' (I've seen this in another clue).
'pass'+'word'='PASSWORD'
Can you help me to learn more?
(Other definitions for password that I've seen before include "key" , "Requirement for logging in" , "It's something to admit" , "Security input" , "Shibboleth - secret phrase to gain admission" .)