Fan in from France on Thursday is coming up a street (10)
I believe the answer is:
enthusiast
'fan' is the definition.
(I know that fan can be written as enthusiast)
'in from france on thursday is coming up a street' is the wordplay.
'in from france' becomes 'en' ('in' in French).
'on thursday' becomes 'thu' (I can't explain this - if you can you should believe this answer much more).
'coming up' shows that the letters should be reversed in order (in a down clue, letters go up).
'street' becomes 'st' (abbreviation).
'is' reversed gives 'si'.
'en'+'thu'+'si'+'a'+'st'='ENTHUSIAST'
Can you help me to learn more?
(Other definitions for enthusiast that I've seen before include "buff" , "Fan" , "One deeply interested in a subject" , "one not at all cool" , "Devotee" .)