Pragmatic approach is adopted by field of study (7)
I believe the answer is:
realism
'pragmatic approach' is the definition.
'is adopted by field of study' is the wordplay.
'adopted by' is an insertion indicator (I've seen this in other clues).
'field of study' becomes 'realm' (I've seen this before).
'is' put within 'realm' is 'REALISM'.
(Other definitions for realism that I've seen before include "Practical approach" , "Reliance on facts" , "Pragmatism" , "Practical quality" , "Art genre that is true to life" .)