Fan strangely hesitant with us (10)
I believe the answer is:
enthusiast
'fan' is the definition.
(I've seen this before)
'strangely hesitant with us' is the wordplay.
'strangely' indicates an anagram.
'with' is an insertion indicator.
'hesitant' is an anagram of 'enthiast'.
'enthiast' enclosing 'us' is 'ENTHUSIAST'.
(Other definitions for enthusiast that I've seen before include "buff" , "Ardent supporter" , "one not at all cool" , "One deeply interested in a subject" , "Devotee" .)