Cheer up tot in depressed area (7)
I believe the answer is:
gladden
'cheer up' is the definition.
(I've seen this in another clue)
'tot in depressed area' is the wordplay.
'tot' becomes 'add' (synonyms).
'in' is an insertion indicator.
'depressed area' becomes 'glen' (I can't justify this - if you can you should give a lot more credence to this answer).
'add' inserted within 'glen' is 'GLADDEN'.
Can you help me to learn more?
(Other definitions for gladden that I've seen before include "Make cheerful" , "Hearten" , "Make pleased or happy" , "Give pleasure to" , "raise spirits" .)