Follows Jack with a night-light! (7)
I believe the answer is:
dogstar
'a night-light' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'follows jack' is the wordplay.
'follows' becomes 'dogs' (I've seen this in another clue).
'jack' becomes 'tar' (both are informal terms for sailor).
'dogs'+'tar'='DOGSTAR'
'with' acts as a link.
Can you help me to learn more?
(Other definitions for dogstar that I've seen before include "animal on TV?" , "This the brightest" , "Bright night light" .)