Pressing metal in Greek capital (7)
I believe the answer is:
ironing
'pressing' is the definition.
(ironing is a kind of pressing)
'metal in greek capital' is the wordplay.
'metal' becomes 'iron' (iron is a metal).
'in greek capital' becomes 'ing' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'iron'+'ing'='IRONING'
Can you help me to learn more?
(Other definitions for ironing that I've seen before include "A housework chore" , "A pressing engagement" , "Laundry job" , "Household task" , "Levelling out" .)