Expensive to have mother in commanding position (7)
I believe the answer is:
primacy
'commanding position' is the definition.
'primacy' can be an answer for 'position' (primacy is a kind of position). I am not sure about the 'commanding' bit.
'expensive to have mother' is the wordplay.
'expensive' becomes 'pricy' (similar in meaning).
'to have' means one lot of letters goes inside another.
'mother' becomes 'ma' (ma can mean mother).
'pricy' placed around 'ma' is 'PRIMACY'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for primacy that I've seen before include "precedence" , "first place" , "Dominance" .)