Gathered in entrance to field, then went astray (8)
I believe the answer is:
inferred
'gathered' is the definition.
('infer' can be a synonym of 'gather')
'in entrance to field then went astray' is the wordplay.
'entrance to' says to take the initial letters.
'then' means one lot of letters go next to another.
'went astray' becomes 'erred' (I've seen this before).
The initial letter of 'field' is 'f'.
'in'+'f'+'erred'='INFERRED'
(Other definitions for inferred that I've seen before include "'Concluded, judged from the facts (8)'" , "Conjectured" , "Rein Fred in because he deduced" , "Deduced by reasoning" .)