Eagle needs to cover Scots valley (4)
I believe the answer is:
glen
'scots valley' is the definition.
(I've seen this before)
'eagle needs to cover' is the wordplay.
'to cover' says the answer is hidden in the clue (I've seen 'covering' mean this).
'GLEN' can be found hidden inside 'eagle needs'.
(Other definitions for glen that I've seen before include "Narrow secluded valley in mountains" , "Highland valley" , "Scottish mountain valley" , "Scottish or Irish valley" , "Valley, dale" .)