Reminisce about subscriber (8)
I believe the answer is:
remember
'reminisce' is the definition.
(to reminisce is to think about the past)
'about subscriber' is the wordplay.
'about' becomes 're' ('re' means regarding or about).
'subscriber' becomes 'member' (I can't explain this - if you can you should give a lot more credence to this answer).
're'+'member'='REMEMBER'
Can you help me to learn more?
(Other definitions for remember that I've seen before include "Recal, recollect" , "Keep in mind" , "Mark" , "Call to mind" , "Be sure" .)