Information about large valley (4)
I believe the answer is:
glen
'valley' is the definition.
(glen is a kind of valley)
'information about large' is the wordplay.
'information' becomes 'gen' (gen can informally mean information).
'about' is an insertion indicator.
'large' becomes 'L' (eg in clothes sizes).
'gen' going around 'l' is 'GLEN'.
(Other definitions for glen that I've seen before include "Narrow secluded valley in mountains" , "Narrow valley with a stream" , "Narrow Scots valley" , "Campbell perhaps" , "Narrow, deep mountain valley" .)