Surprisingly mean girl hardly developed (8)
I believe the answer is:
germinal
'hardly developed' is the definition.
The answer and definition are not the same part of speech. However, past participle verbs and adjectives occasionally define each other.
'surprisingly mean girl' is the wordplay.
'surprisingly' indicates an anagram (a surprising ordering of the letters).
'mean'+'girl'='meangirl'
'meangirl' is an anagram of 'GERMINAL'.
Can you help me to learn more?
(Other definitions for germinal that I've seen before include "Novel by Zola; in an early stage of development" , "Rudimentary" , "In the earliest stage of development, like new ideas" , "Embryonic; Zola novel" , "a month after the French Revolution" .)