Females are not soft-hearted dopes! (4)
I believe the answer is:
does
'females' is the definition.
(female deer)
'not soft-hearted dopes' is the wordplay.
'not soft' becomes 'doe' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'hearted' indicates the central letters.
'dopes' becomes 'grasses' ('grass' can be a synonym of 'dope').
The middle letter of 'grasses' is 's'.
'doe'+'s'='DOES'
'are' acts as a link.
Can you help me to learn more?
(Other definitions for does that I've seen before include "Acts" , "is active" , "herbivores" , "about 50% of deer" , "Suffices" .)