Criminal starts to take hostages in every field (5)
I believe the answer is:
thief
'criminal' is the definition.
(I know that criminal can be written as thief)
'starts to take hostages in every field' is the wordplay.
'starts to' indicates taking the first letters.
The first letters of 'take hostages in every field' is 'THIEF'.
(Other definitions for thief that I've seen before include "One who steals" , "Aus. or Scots city" , "Unlawful taker" , "Raffles, say" , "Larcenist" .)