Information about lake in valley (4)
I believe the answer is:
glen
'valley' is the definition.
(I know that glen is a type of valley)
'information about lake' is the wordplay.
'information' becomes 'gen' (gen can informally mean information).
'about' indicates putting letters inside.
'lake' becomes 'L' (geographical abbreviation).
'gen' going around 'l' is 'GLEN'.
'in' is the link.
(Other definitions for glen that I've seen before include "Scottish mountain valley" , "Long narrow valley in Scotland" , "Narrow valley with a stream" , "Narrow Scots valley" , "Narrow secluded valley in mountains" .)