Doughty at heart, fondle ferret (4)

I believe the answer is:

grub

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'ferret' is the definition.
(both can mean to search for something)

'doughty at heart fondle' is the wordplay.
'at heart' says to take the centre.
'fondle' becomes 'rub' (I can't justify this - if you can you should give a lot more credence to this answer).
The central letter of 'doughty' is 'g'.
'g'+'rub'='GRUB'

Can you help me to learn more?

(Other definitions for grub that I've seen before include "Food - worm" , "Beetle larva" , "Dig (up); hack writers' Street" , "Dig - maggot - food" , "Slangy food or kind of larva" .)

I've seen this clue in The Times.

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