Feeling down at heart indeed? Iron and iron right away (10)
I believe the answer is:
depression
'feeling down' is the definition.
(down can mean sad or depressed)
'heart indeed? iron and iron right away' is the wordplay.
'heart indeed?' becomes 'de' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'iron' becomes 'press' (I've seen this in another clue).
'and' says to put letters next to each other.
'right' becomes 'r' (common abbreviation).
'away' suggests deleting specific letters.
'iron' with 'r' taken away is 'ion'.
'de'+'press'+'ion'='DEPRESSION'
'at' acts as a link.
(Other definitions for depression that I've seen before include "gloom" , "mental anguish" , "valley" , "Pit" , "Nineteen twenty nine financial slump" .)