Fellow has lapse on field in bewilderment (3)
I believe the answer is:
fog
'bewilderment' is the definition.
(thesaurus)
'fellow has lapse on field' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'has' says to put letters next to each other.
'lapse on field' becomes 'og' (I can't explain this - if you can you should believe this answer much more).
'f'+'og'='FOG'
'in' is the link.
(Other definitions for fog that I've seen before include "Obscure" , "Bafflement" , "second growth of grass" , "Miasma" , "Bank restricting visibility" .)