Fading colour you see in midnight (8)
I believe the answer is:
reducing
'fading' is the definition.
The definition and answer can be both related to bodily activities as well as being present participle verbs.
Maybe you can see a link between them that I can't see?
'colour you see in midnight' is the wordplay.
'colour' becomes 'red' (red is a kind of colour).
'you' becomes 'u' (commonly used in online communication).
'see' becomes 'C' (the word for the letter, according to Chambers).
'midnight' becomes 'g' (the middle letter in 'night').
'red'+'u'+'c'+'in'+'g'='REDUCING'
Can you help me to learn more?
(Other definitions for reducing that I've seen before include "Making smaller" , "Cutting down" , "Bringing down, lowering" .)