In a way, a half of bitter is always diluted (6)
I believe the answer is:
watery
'always diluted' is the definition.
'watery' can be an answer for 'diluted' (similar in meaning). I am not certain of the 'always' bit.
'in a way a half of bitter' is the wordplay.
'in' means one lot of letters goes inside another.
'a half of' suggests halving the letters.
'bitter' cut in half is 'ter'.
'way' going around 'ter' is 'WATERY'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for watery that I've seen before include "(Of food) thin, tasteless" , "Overly diluted, thin" , "Insipid" , "Weak, too diluted" , "Dilute; weak, pale" .)