A depression mostly overcome by doctor's lively dance (5)
I believe the answer is:
galop
'lively dance' is the definition.
(I've seen this before)
'a depression mostly overcome by doctor's' is the wordplay.
'depression mostly' becomes 'lo' (I can't justify this - if you can you should give a lot more credence to this answer).
'overcome by' is an insertion indicator.
'doctor' becomes 'gp' (general practitioner).
'a'+'lo'='alo'
'alo' placed into 'gp' is 'GALOP'.
Can you help me to learn more?
(Other definitions for galop that I've seen before include "Couple dance" , "Nineteenth-century dance" , "Lively ballroom dance" , "dance music" .)