Milan team lacking energy in defence: routine thing! (5-2-5)
I believe the answer is:
stock in trade
'routine thing' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'milan team lacking energy in defence' is the wordplay.
'milan team' becomes 'Inter' (Inter Milan football team).
'lacking' is a deletion indicator.
'energy' becomes 'e' (physics symbol as in E=mct).
'in' is an insertion indicator.
'defence' becomes 'stockade' (stockade is a kind of defence).
'inter' with 'e' taken out is 'intr'.
'intr' inserted into 'stockade' is 'STOCK-IN-TRADE'.
Can you help me to learn more?
(Other definitions for stock in trade that I've seen before include "goods for sale" , "Typical commodity dealt with in one's occupation" , "Typical commodity a person deals in" , "Typical activity of a person or company" , "Goods necessary to a business" .)