Like the accent of a number at the space administration (5)
I believe the answer is:
nasal
'like the accent' is the definition.
I can't judge whether this defines the answer.
'a number at the space administration' is the wordplay.
'a number' becomes 'L' (fifty in Roman numerals).
'at' means one lot of letters go next to another (I've seen this in other clues).
'the space administration' becomes 'nasa' (I can't explain this - if you can you should give a lot more credence to this answer).
'l' after 'nasa' is 'NASAL'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for nasal that I've seen before include "To do with nose, say sound" , "Relating to one's hooter" , "Part of helmet" , "Relating to a facial organ" , "Twangy" .)