Light with a tendency to grow less? (5)
I believe the answer is:
taper
'light' is the definition.
(taper is a kind of light)
'a tendency to grow less?' is the wordplay.
I cannot really understand how this works, but
'a' could be 'per' (eg 'one a day' means 'one per day') and 'per' is located in the answer.
The remaining letters 'ta' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'with' acts as a link.
Can you help me to learn more?
(Other definitions for taper that I've seen before include "Spill - become narrower towards one end" , "Get narrower towards end" , "recording artist" , "Waxed spill" , "Thin wick" .)