Longing to see area in East Germany (5)
I believe the answer is:
Here is my best explanation:
'longing' is the definition.
'area in east germany' is the subsidiary indication.
'area' becomes 'a' (maths abbreviation).
'in' is an insertion indicator.
'east' becomes 'e' ('E' can be a synonym of 'east').
'germany' becomes 'ger' (I've seen this in other clues).
'a' inserted inside 'eger' is 'eager'.
'to see' is the link.
(Other definitions for eager that I've seen before include "Raring to go", "Enthusiastic, avid", "Keen (as a beaver?)", "Showing keen interest", "Earnest", "Enthusiastic, raring to go", "Avid, enthusiastic", "Avid, very keen", "Keen - enthusiastic" and "Impatient".)