Reluctance to move grey hat fixed on lady's head (8)

I believe the answer is:

lethargy

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'reluctance to move' is the definition.
I can't tell whether this definition defines the answer.

'grey hat fixed on lady's head' is the wordplay.
'fixed' is an anagram indicator.
'on' is a charade indicator (letters next to each other).
'head' indicates taking the first letters.
The first letter of 'lady' is 'l'.
'grey'+'hat'='greyhat'
'greyhat' anagrammed gives 'ethargy'.
'ethargy' put after 'l' is 'LETHARGY'.

Can you help me to learn more?

(Other definitions for lethargy that I've seen before include "Inertia" , "Stringed instrument" , "Weariness" , "state of apathy" , "Extreme lack of energy, listlessness" .)

I've seen this clue in The Independent.

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