Miss Lynn in time becomes mean (7)
I believe the answer is:
average
'mean' is the definition.
(I know that mean can be written as average)
'miss lynn in time' is the wordplay.
'miss lynn in' becomes 'aver' (I can't explain this - if you can you should give a lot more credence to this answer).
'time' becomes 'age' (an age is a period of time).
'aver'+'age'='AVERAGE'
'becomes' acts as a link.
Can you help me to learn more?
(Other definitions for average that I've seen before include "It's common" , "nothing special" , "Of no exceptional quality or ability" , "mean maybe" , "The statistical norm" .)