Some sportsmen, thus, I astonished as fan (10)
I believe the answer is:
enthusiast
'fan' is the definition.
(thesaurus)
'some sportsmen thus i astonished' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'ENTHUSIAST' is hidden within 'sportsmen thus i astonished'.
'as' is the link.
(Other definitions for enthusiast that I've seen before include "Ardent supporter" , "One deeply interested in a subject" , "Fan" , "buff" , "Devotee" .)