The first man on Mars? The first woman, with due respect! (5)
I believe the answer is:
madam
'woman with due respect' is the definition.
(respectful term of address for a woman)
'the first man on mars? the first' is the wordplay.
'the first man' becomes 'adam' (first man in the Bible).
'on' is a charade indicator (letters next to each other).
'the first' indicates taking the first letters.
The initial letter of 'mars' is 'm'.
'adam' put after 'm' is 'MADAM'.
(Other definitions for madam that I've seen before include "Woman with status - girl with bad manners" , "Stuck-up girl" , "Palindrome used in speaking politely to a woman" , "Leader of House of Congress" , "How one may address a woman" .)