Mother in going into showing first and last extremes of love (10)

'mother in going into showing first and last extremes of love' is the definition.
I can't tell whether this definition defines the answer.

'mother in going into showing first and last' is the wordplay.
'going into' indicates putting letters inside.
'first and last' says to hollow out the word (remove centre letters) (only the first and last letters are used).
'showing' with its middle taken out is 'sg'.
'mother'+'in'='motherin'
'motherin' going into 'sg' is 'SMOTHERING'.

Can you help me to learn more?