Doughty at heart, fondle ferret (4)
I believe the answer is:
grub
'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 am not sure about this - if you are sure you should give a lot more credence to this answer).
The centre 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" .)