Learner guided up wooded hollow (4)
I believe the answer is:
dell
'wooded hollow' is the definition.
(I've seen this before)
'learner guided up' is the wordplay.
'learner' becomes 'l'.
'guided' becomes 'led' ('lead' can be a synonym of 'guide').
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'l'+'led'='lled'
'lled' back-to-front is 'DELL'.
(Other definitions for dell that I've seen before include "Small wooded hollow or valley" , "Small secluded valley" , "Small valley, rhymes with tumbled down" , "Farmer's place, in song" , "Manufacturer that relies heavily on Silicon" .)