Beginning to get cheap light radiation (4)
I believe the answer is:
glow
'light radiation' is the definition.
'glow' can be an answer for 'radiation' (glow is a kind of radiation). I'm not certain of the 'light' bit.
'beginning to get cheap' is the wordplay.
'beginning to' indicates taking the first letters.
'cheap' becomes 'low'.
The initial letter of 'get' is 'g'.
'g'+'low'='GLOW'
Can you help me to learn more?
(Other definitions for glow that I've seen before include "Gleam" , "Emit light and heat without flame" , "Radiate or redden" , "Shine with warmth, emotion" , "Give out light without flames" .)