Days, weeks, months passing by (5)
I believe the answer is:
times
'by' is the definition.
(I've seen this before)
'days weeks months passing' is the wordplay.
I cannot really see how this works, but
'months' could be 'm' and 'm' is located in the answer.
The remaining letters 'ties' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for times that I've seen before include "Thunderer?" , "Paces" , "- - they are a-changin'" , "''For the ..., they are a'changin'''(Bob Dylan)" , "See 10" .)