Real colour of one unswervingly faithful (4,4)
I believe the answer is:
true blue
'faithful' is the definition.
(I've seen this before)
'real colour of one unswervingly' is the wordplay.
I cannot quite understand how this works, but
'real' could be 'true' (similar in meaning) and 'true' is present in the answer.
'colour' could be 'blue' (blue is a colour) and 'blue' is located in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for true blue that I've seen before include "Staunchly loyal (Tory?)" , "Staunch Tory" , "Colour of unswerving loyalty" , "Very much Conservative" , "Loyal follower" .)