Madly in love, I’m putting Romeo in the shade (9)
I believe the answer is:
vermilion
'shade' is the definition.
(I've seen this before)
'madly in love i'm putting romeo' is the wordplay.
I cannot quite see how this works, but
'love' could be 'o' (love means zero in tennis) and 'o' is found in the answer.
'in' is found in the answer.
'romeo' could be 'r' (phonetic alphabet: alpha, bravo, charlie etc.) and 'r' is present in the answer.
This may be the basis of clue (or it may be nonsense).
'in the' acts as a link.
Can you help me to learn more?
(Other definitions for vermilion that I've seen before include "Vivid red (with an orange tinge?)" , "Bright scarlet" , "Brilliant red" , "Bright red colour" , "Ron, I'm live with a bright red pigment" .)