Insistent 80s pop star (7)
I believe the answer is:
adamant
'insistent' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for adamant that I've seen before include "Positive or intransigent" , "Refusing to budge" , "Completely determined" , "unshakeable in purpose" , "Inflexible, obdurate" .)