You are said to support a fellow enthusiast (7)
I believe the answer is:
amateur
'enthusiast' is the definition.
(thesaurus)
'you are said to support a fellow' is the wordplay.
'you' becomes 'u' (I've seen this in other clues).
'said' indicates a 'sounds like' (homophone) clue.
'to' means one lot of letters go next to another (I've seen this in other clues).
'support a fellow' becomes 'amate' (I can't explain this - if you can you should give a lot more credence to this answer).
'are' sounds like 'r'.
'u'+'r'='ur'
'ur' put after 'amate' is 'AMATEUR'.
Can you help me to learn more?
(Other definitions for amateur that I've seen before include "Unpaid (sport)" , "Layman" , "Unpaid practitioner" , "Tum area (anag.)" , "Dilettante: buff" .)