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 unsure 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' indicates taking half.
'bitter' with half the letters taken is 'ter'.
'way' enclosing '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" .)