Relative of the red admiral (3)
I believe the answer is:
dad
'relative' is the definition.
(I know that dad is a type of parent)
'of the red admiral' is the wordplay.
'of' says the answer is hidden in the clue.
'DAD' can be found hidden inside 'red admiral'.
(Other definitions for dad that I've seen before include "Popular father - a palindrome" , "Pa" , "Mum's mate" , "Father, in short" , "Old man" .)