Cautiously introduce power — owns home without energy (5,2)

I believe the answer is:

phase in

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'cautiously introduce' is the definition.
'phase in' can be an answer for 'introduce' (phasing in is a kind of introducing). I'm not sure about the 'cautiously' bit.

'power owns home without energy' is the wordplay.
'power' becomes 'p' (symbol in physics).
'owns' becomes 'has' ('have' can be a synonym of 'own').
'home' becomes 'in' ('he's home' can mean 'he's in').
'without' indicates putting letters inside ('without' can be similar in meaning to 'outside').
'energy' becomes 'e' (physics symbol as in E=mc2).
'has'+'in'='hasin'
'hasin' enclosing 'e' is 'hasein'.
'p'+'hasein'='PHASE IN'

Can you help me to learn more?

(Other definitions for phase in that I've seen before include "introduce slowly" , "Introduce gradually" , "Introduce by stages" .)

I've seen this clue in The Times.

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