Not a minute without being seen? (7)
I believe the answer is:
unnoted
'without being seen?' is the definition.
I can't judge whether this definition defines the answer.
'not a minute' is the wordplay.
'not' becomes 'un' (prefix meaning 'not').
'a minute' becomes 'noted' (I am not sure about this - if you are sure you should believe this answer much more).
'un'+'noted'='UNNOTED'
Can you help me to learn more?
(Other definitions for unnoted that I've seen before include "Not taken into account" , "Not recognised" .)