Paper around large field (5)
I believe the answer is:
realm
'field' is the definition.
(synonyms)
'paper around large' is the wordplay.
'paper' becomes 'ream' (I've seen this before).
'around' indicates putting letters inside.
'large' becomes 'L' (eg in clothes sizes).
'ream' going around 'l' is 'REALM'.
(Other definitions for realm that I've seen before include "Kingdom, domain" , "Area of knowledge under discussion" , "field of study" , "Kingdom could be lamer" , "where ruler holds sway?" .)